Tag Archives: integrated

In December of 2021, my first review in The Absolute Sound was published—the HiFi Rose 150B streaming DAC. I thought so highly of the product that I bought the review sample, and it remains the core of my apartment system. I was delighted when attending AXPONA this year (well, weren’t we all delighted to be attending shows again?) to find that Rose had just released a new integrated amplifier, the RA180. For those not familiar with HiFi Rose, it is a relatively new company from Korea focused on streaming DACs. The RA180 is the company’s first product that does not include a DAC.

When I set eyes on this integrated amplifier, it was love at first Rose. One can’t deny the industrial design’s ingenuity. If someone asked me before seeing it what I would have expected a HiFi Rose integrated amplifier to look like, I would have responded “Super-clean like its streaming DAC, with a kind of minimalistic Scandinavian design.” As it turns out, this design is quite the opposite. About the only thing it has in common with the aesthetic of the company’s streaming DAC is the wonderful milled-aluminum outer case. Everything else is different. The faceplate has a retro, steam-punk look that absolutely works. It has the perfect balance of grit and elegance. Honestly, this piece is so good looking that it could’ve sounded terrible, and I’d still have wanted it in my equipment rack.

While its looks were nothing short of gorgeous, it was the sound of the $6995 RA180 that really drew me in. When I heard the HiFi Rose at AXPONA, it was driving Piega speakers, which I’m familiar with. Piegas tend be extremely revealing—sometimes almost to a fault. If there is any grain or harshness, particularly in the treble, Piega speakers will reveal it in a most unflattering way. That’s what really struck me about the RA180; there was no grain, no harshness, and no hint of sound that would bring on listener fatigue. The presentation was incredible relaxed, full bodied, and enjoyable. I quickly let Jon Derda of MoFi Distribution know that I was interested in a review sample.

The Technology and Design

When I interviewed Sean Kim, founder and president of HiFi Rose for the RS150B review, he emphasized that the most important aspect of the company’s designs was sound quality. He wasn’t after “great” sound; his goal was to make the “best” sound.

The RA180 is based on a Class D output stage, a technology that I’ve heard sound good in some cases and not very good in quite a few others. According to Kim, the primary issue with Class D amplifiers is the “dead time” between pulses when both transistors in the opposing pair are turned off. To shorten this dead time, HiFi Rose uses GaN (gallium nitride) transistors and increased the switching frequency to 100kHz. Kim also wanted the RA180 to have a phonostage along with true bi-amping capability, with four independent amplifiers within the RA180’s chassis.

The RA180s four separate amplifiers with bi-amplifying capability is unique in that it offers four possible configurations: First, two of the RA180’s 200W amplifiers (into 8 ohms) can drive a pair of speakers with a single pair of input jacks—nothing special here. Second, bi-wirable speakers can be driven by all four of the RA180’s amplifiers; two amplifiers drive the pair of speaker’s low-frequency sections and the RA180’s two additional amplifiers drive the pair of speaker’s midrange/tweeter sections. The third option is to bridge the amplifier channels to drive single-wire speakers (“BTL Mode”), increasing the RA180’s output power to 400Wpc. Finally, the RA180 offers the option of engaging a high-pass filter on one pair of amplifiers specifically to drive a super-tweeter. In this configuration, two of the RA180’s amplifiers drive the full-range speaker, and two drive the super-tweeter with a frequency-response-optimized signal with frequency extension to 100kHz. This flexibility allows you to optimize the RA180 for your system, as well as to change configurations in the future as your system evolves.

Initial Setup

Setting up the RA180 is straightforward. There are three pairs of single-ended inputs, one phono input, and a pair of balanced inputs. A rear-panel switch selects between mm or mc gain. A front-panel control lets you choose different phono equalization curves, but there’s no cartridge-loading adjustment. (I did not use a turntable with this unit, so was not able to evaluate the phono input.) A 12V trigger and IR control round out the rear panel. The inclusion of these control jacks allows the RA180 to be controlled by external automation systems.

The outputs are a little less straightforward. There are 16 binding posts on the rear panel. It took me a little while to figure them all out. First off, these outputs offer the ability to drive two separate sets of speakers, as well as to bi-amp one or both sets of speakers (hence the need for 16 binding posts). There is also one RCA output jack to drive a subwoofer, a useful feature.

Most high-end electronics today eschew bass and treble controls, but not the RS180. The last time I had a system with tone controls was in the 70s. Fortunately, there is a bypass switch to remove the tone controls from the signal path. There is also a “pure direct” input, which bypasses the preamplifier section altogether, turning the RA180 into a power amplifier.

Initial Listening

I started in the regular (200Wpc) mode, thinking this would supply more than enough power. In fact, it did. Indeed, I was able to reduce the output of the HiFi Rose 150B streaming DAC feeding the RA180. The review sample was a brand-new unit, which to my knowledge had not been burned in, so I expected to hear the usual unimpressive sound with the usual grain, dynamic restraint, and imbalance that naturally occur as components break in. That was not the case. Right out of the box, during the first minute of listening, the RA180 was much more enticing than what I was accustomed to on my system. I immediately noticed a superior balance top to bottom. I expected this from a solid-state design, but what I did not expect was the openness of the overall presentation. Most solid-state amps I’ve used in the past were very constrained until they had been burned in for at least a few hundred hours. This was immediate bliss. I was wondering if it was going to get better (it was a little hard to imagine that it could), but while listening intently in the first week of burn-in I did notice subtle improvements.

Everyday Use

I think it’s important to consider how a unit performs playing background music. Not all listening has to be critical, with you seated in the sweet spot, concentrating on every cue. My current system is in the main living area, which is also the kitchen, my home office, and the dining room…well, you get the point. When the system is in a shared space like this, it’s also a shared system. Other family members need to be able to use the system independently. It should be ergonomically intuitive. This is the only area that I really had some questions about the RA180’s design.

It all has to do with remote functions. It’s important to consider how one uses the equipment on a day-to-day basis. The remote for the RA180 is an infrared model with a rear-panel input plug for custom installations. Bravo to HiFi Rose for that, as I was not super-happy about the Bluetooth remote for its streaming DAC. The RA180 remote also has direct access to each of the inputs (rather than one-up/one-down input selection). Another plus for Rose. Unfortunately, I had to scratch my head when I realized that the two different remote technologies were not cross-compatible. Although I was not a fan of the Bluetooth remote for the streaming DAC, I’m less of a fan of using two remotes, and perhaps a tablet as well, to select music. It would be really nice if one remote could control both products within a manufacturer’s product line. In the grand scheme of things, this is a minor point and one that did not hinder my enjoyment of the RA180, but I felt that for some readers it could be important and should be mentioned.

Other than that small demerit, ergonomics and ease of use were terrific. Anyone in the family can easily use the RA180 without dreading that he or she will press the wrong button.

Serious Listening

After a few weeks of burning in the unit, I felt the RA180 was ready to really be listened to. I have a method for going about serious listening when I’m evaluating any product, which I have not described previously and feel is worth mentioning. First, I regularly listen to a lot of different types of music—from large-scale classical to chamber music, jazz of all types (female vocal being my favorite), rock, pop, and R&B. When I evaluate any product or when listening at a show, I always like to hear a broad range of music. It’s rare to find a system that does everything exceptionally well, and the ones that do are often well out of my price range. My system does most everything well, as it doesn’t tend to favor one type of music over another. A good example of this is to consider horn-based speakers versus planar speakers. Horns tend to deliver great dynamics but may lack spatial nuances in the soundstage. Rock music and large orchestral works tend to be favored by these speakers. Planar speakers are quite the opposite, as they provide excellent spatial cues and detail but lack the dynamics. Female vocals and chamber works tend to sound best with these speakers. Depending on the speakers selected, appropriate amplification must be chosen to match, as well.

The tube amps that I had been using prior to installing the RA180 were push-pull KT88-based and had very good dynamics with reasonably flat frequency response. Tube-based amplifiers in general will have a lower damping factor than solid-state counterparts—that is, less ability to control the woofer’s motion after the drive signal has stopped. This became extremely apparent while listening to the RA180. The RA180 exhibited much more control in the bottom end on complex orchestral music such as Stravinsky’s The Firebird. The amplifier seemed to have no bounds. It could certainly play far louder than I would ever want to hear, but even at relatively high volumes, it just seemed effortless from top to bottom. Normally, I find large dynamic passages can cause other instruments, particularly strings, to either fade out or take on an unpleasant edge and grain. Not with this amp. Everything stayed together in the right place with the right tonality, no matter the level.

I decided to go to one of my favorites for testing, János Starker playing Bach’s Cello Suites. You’ll probably find I use this piece a lot in my reviews, and it’s because it can reveal all sorts of problems in a system. If there is an imbalance from the upper bass through the mids, it will be exposed. This is particularly true for any crossover problems (this was a piece we used regularly to test for these issues when I was working with Talon Speakers). I decided it was time to try the BTL mode that bridges the four 200W amplifier channels into two 400W channels. I first started listening without BTL to Suite No. One. It sounded terrific. It was full, balanced, and excellently detailed. There was no hint of coloration or other flaws that I could detect. I then switched over to the BTL mode, which combines two channels and increases the output. (I reduced the signal output from the HiFi Rose 150B to 1000mV to compensate.)

HiFi Rose says BTL is for difficult loads. My speakers certainly are not, but I had to try it. What I found was a smoother, more fleshed-out soundstage. Staging was already really good, but this just made it sound more organic. The cello had better dimensionality, weight, and resonance within the larger soundstage than it had before. It sounded more natural. There was no question in my mind that BTL was better, so I did the remainder of my listening in this mode.

Hugh Masekela’s Grazing in the Grass is wonderfully recorded and did not disappoint. The bass was fuller and better defined than I had heard before on my system. The soundstage was beautifully presented from left to right, though on this recording there’s not a lot of depth. I then moved to large-scale classical music with Mahler’s Ninth Symphony This piece is one I find to be particularly challenging for many systems. It’s so complex, with minute details occurring at the same time as large crescendos. Most systems can do some passages well, but almost all have gaps where they can’t perform. Now remember, we are not listening to a cost-no-object system, so expectations should be reasonable. At higher levels, I know I will get some compression, but while temporarily living in an apartment, I don’t have speakers that can move enough air at convincing volumes for this piece. However, I can play loud enough without compression to know if an amplifier is able to deliver. The RA180 performed without flaw. What I really would have loved to do was connect it to some much larger and possibly more difficult-to-drive speakers to see how far this integrated amplifier could go. From what I could detect, it had a lot of horsepower to spare, and I would need to go a long way to even begin to push its limits. I would expect this unit could drive all but the most difficult and inefficient speakers out there with ease.

Much of my listening is jazz with a lot of female vocal jazz selections. Recently, Roon had mixed a “Kandice Springs” playlist for me that my wife and I listened to for at least an hour and a half. It wasn’t critical listening, but we were seated in a good position, listening at a level comfortable enough to have a conversation. There were a few times I had to stop and really focus on the music because it just sounded so good. The sound was natural and relaxed, with absolutely no strain. Tonality, definition, and soundstage were consistently right on. The fact that I was pulled into the music without conscious effort, because the sound was so good, is a major win for this product and speaks volumes for its future success.

Conclusion

After reviewing the HiFi Rose 150B streaming DAC, I was so impressed that I purchased the review sample. It has remained the digital heart of my system. The RA180 ranks in the same league as the HiFi Rose 150B. It offers value both in build and sound quality, significantly surpassing its price point. This unit has the headroom to handle just about any speaker. And while sound quality is certainly the most important criterion, I must say, again, that the industrial design of this unit is spectacular. HiFi Rose is a relative newcomer to this market, but there’s no doubt the company is here to stay.

Specs & Pricing

Inputs: Three single-ended on RCA jacks, one balanced on XLR jack, one phono, selectable mm or mc.
Output: Subwoofer out on RCA jack
Power output: 200Wpc into 8 ohms (four channels); 400Wpc into 8 ohms (two channels)
Dimensions: 16.9″ x 5.1″ x 13.8″
Weight: 36.8 lbs.
Price: $6995

HIFI ROSE (MoFi Distribution, U.S. distributor)
mofidistribution.com

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