Comparing amplifiers is somewhat like comparing different varieties of vanilla ice cream. While all might be appealing, distinguishing their differences can be challenging. Over the years, I have owned many amplifiers, mainly low-powered tube, DIY FirstWatt, and Class D amps. At the time, I had Tekton Moabs, which I preferred over my Magnepan 3.7s. However, after hearing a friend’s 3.7s powered by a D'Agostino S350, I realized I had not tried the appropriate amplifier for the Maggies. Unable to afford the S350, I purchased used PS Audio BHK 300s at a reasonable price and was very happy with them. The 3.7s replaced the Moabs in my main system, and eight months later, I upgraded to the Magnepan 20.7s. Currently, I am using the Final Audio M35s, acquired in January.
Last December, a static shock affected my entire system, putting one of the BHK 300s into a fault mode. PS Audio repaired it at a reasonable cost, though it took some time due to the holidays. In the interim, a friend lent me his CODA Continuum TS, which did not meet my expectations. Consequently, I sought an affordable replacement and found a Krell FPB 300 locally at a good price. Buying that opened the floodgates and now, 3 months later, I find myself owning 5 very good high-powered amps to use with my Final M35s
A friend had raved about the Halcro amps many months ago and the top of the line DM-88 came up for sale at the end of December and I bought those. And recently I got a Plinius SA 103. And I am getting a pair of Krell FPB 650M monoblocks at the end of March. All these amps were extremely well reviewed when they first came out and all of them have ardent fans.
So, on top of listening closely to the M35s as they have burned in, I have also been obsessively comparing amplifiers hoping to find the one that is best suited to my new speakers. Unfortunately, I think amps are going to be like ice cream, and none of the amps I own will be the best with all the different flavors of music I enjoy.
All the amps perform well with the Final M35s and none of them have any problem with the M35s dip down to 2 Ohms at 14 kHz. There is some variation in how prominent things like cymbals and chimes are and without putting a different speaker in the system it is difficult to tell how much of that is from how the amp sounds vs that dip in impedance.
Testing involved a Luxman AS-50R remote-controlled speaker selector switch and consistent speaker cables. Different XLR cables—Harmonic Magic Link 2 XLRs and Silversmith Fidelium ribbon XLRs—were used, potentially introducing sonic differences. Level matching was performed with pink noise and a 1 kHz test tone within 0.5 dB controlled via the preamp.
The Halcro DM-88s have a distinctive sound. They are extremely detailed and nuanced and probably have the best, largest soundstage. They are also the least dynamic sounding, and many recordings seem a little flat in comparison to the other amps. People who don’t like Halcros describe them as being lifeless, but I think a more accurate description would be burnished. They are smoother, and more nuanced but lack some punch and pizzaz. They handle low level texture and tonality extremely well and the bass is strong and well defined. There is a lot of air, but highs are a bit less prominent. You might describe them as being polite. In spite of being the least lively of the amps I keep coming back to them and so far have always felt I am missing some aspects of the music with the other amps.
The Krell FPB 300 initially struck me as being a bit coarse, more of a balls to the wall party animal, but I think they may have just needed more time to warm up. They have a reputation for excellent bass and I feel that is true. There is a depth and palpability to a lot of drum tracks that is fantastic. The bass is a little flabbier than the DM-88s but that might well be in the music. They aren’t bloated. They are dynamic without being exaggerated and the mid-range is very satisfying. The top end has a bit more sparkle than the DM-88s and I like that. On very close listening you can tell that the inner detail is less than the DM-88s and the soundstage is a tad less holographic. Tonally they have a slightly different flavor but I’m not sure if describing them as a bit warmer and the DM-88s as a bit cooler is quite right, but it is the best I’ve got. Overall, the FPB 300s sound very good. The extra punch isn’t exaggerated, and it suits a wide range of music. They have about 2.5 dB more gain than the DM-88s. The FPB 300 runs very hot and I put fans on the heatsinks.
The Plinius SA 103 sounds very similar to the Lamm M2.2’s that a friend lent me a few months ago. They have a lot of gain, with an XLR connection they are +5 dB vs the FPB 300s and +7.5 dB vs the DM-88s. In my system that is too much for a lot of the music I play. Streaming contemporary music over the Holo May KTE DAC I have to lower the volume on my Audio Research Ref 5SE preamp to below 20 and to my ears that decreases quality. Switching to the RCA input fixes that but then you lose some of the distinctiveness of the SA 103s so I didn’t listen that way for long. The SA 103 strikes me as a mid-range monster. They are extremely dynamic sounding with a ton of punch and excitement and a warm lush mid-range. But even level matched closely I often found the music sounded too loud for my tastes. I think about it like a color photograph that has had it’s contrast and saturation boosted. It has a lot of impact but for me it often seemed a little unnatural. I also found it to be less detailed than either the DM-88s or FPB 300s. It doesn’t have that same holographic quality that those other amps have. The SA 103 does have a ton of presence, and it makes a very positive first impression, but I liked it less the more I listened to it. I suspect that the people that rave about this amp have fairly specific tastes. The person I bought it from gave me a long list of well-regarded other amps he had owned that he preferred the SA 103 to, but I don’t think it is going to be the right amp for me.
I took that PS Audio BHK 300s out of the system a couple of weeks ago after comparing them to the DM-88s and the FPB 300s. Frankly, I had been completely happy with the BHK 300s and I wouldn’t have started down this amp journey if I hadn’t blown one of the channels. When I was comparing them to the DM-88s I kept finding myself preferring the tone and soundstage of the Halcros even though the BHK 300s had better dynamics. At the end of the day, I just found myself being more satisfied with the DM-88s. These are the only two amps I compared extensively with the Magnepan 20.7s as well as the M35s. If anything, I liked the DM-88s even more with the 20.7s than I did with the M35s. Comparing the FPB 300s I felt I was capturing more of the better soundstage of the Halcros while retaining the better dynamics of the BHK 300s. I also felt the FPB 300s had more detail and a bit more top end sparkle. At the end of the day, I found myself preferring the FPB 300s and didn’t hear a place the BHK 300s seemed particularly better. Now I will say the BHK 300s have tubes in the input section and even though I have a variety of different tubes to try there these listening tests were done primarily with Amperex Bugle Boy 6DJ8/ECC88 tubes. The tubes do make a difference, and I would try different tubes before I reached any final decision about the BHK 300s.
The Krell FPB 650Ms come at the end of this month. Those are monstrous 650 watt monoblocks that have a reputation for being noticeably better than the FPB 300s. I guess time will tell.
I’m afraid the conclusion that I’ve reached is a bit unsatisfying. Just like different flavors of vanilla ice cream, where you might find you prefer one variety with brownies and another with apple pie, I continue to find I prefer different amps with different genres of music and haven’t found one that is the best across all my listening. None of the amps perform poorly with the M35s and I can’t imagine anyone would be unhappy with how any of them sound. The differences I described are less than the similarities. Perhaps the Krell FPB 650Ms will bring me to audio nirvana, but it is more likely that the perfect amp is either just a dream or beyond my budget!
