The amplifier now has some 50 hours of burn-in. Therefore I can now do the review:
Speaker used: Martin-Login Montis electrostatic loudspeaker with powered woofer
Pre-amp: DCB1 hot-rod (high-current, shunt-regulated buffer) with DACT 21 style shunt attenuator (I am now listening with just my attenuator)
DAC: Eastern Electric Mini-Max Supreme 12AU7 buffered ES9018
interconnects: pure-silver in PTFE insulator
Source: Tidal music accomplished via Roonlabs from a dedicated Windows 10 server.
Amplifiers compared: VHEX+ and Aleph J (both built by me)
I didn't really know what to expect with this amplifier. I had never owned a Class-A amplifier of this power rating. With my incredibly sensitive loudspeaker I knew that it would be enough power, but would it be different from others amps I've heard, such as the Aleph J that I built?
So, I started off with Adele 25, Hello
Adele's vocals on this album are stunning and breathtaking, my jaw dropped with the clarity that the USSA-5 was revealing. You have to understand that my loudspeaker, with ~500 sq. in. of radiating area reveals everything in both the recording and the equipment: nothing can hide from this speaker, nothing. Now back to the vocals.
What I hear from this amplifier in this recording is each track of the stiched together by recording engineer Ariel Rechtshaid. I've heard this type of clarity before in an amplifier, but I've never heard warmth and the focus like this. A transcendent experience.
Hearing that focus is incredibly rare from a piece of audio equipment. What the USSA-5 does is peel back the the layers (banana peel if you so choose) and allows the recording to be heard. Another way to describe this amplifiers sound would be that of headphones: the presentation is tightly focused right at the listener. Not to say that the presentation is too forward or too narrow. It is not. What it is brilliance in engineering.
The reality is, that although this is a simple amplifier in name and parts count, it is not in its design. Each iteration of the USSA-5 has built upon and benefited from the experiences of each iteration. When it comes to engineering anything, IMHO, circuit design is number one, followed by active devices, then distantly by passive. So, you can buy all the boutique audio parts you want, but they will not help a poor design. For that reason, I built the USSA-5 with those parts specified in the BOM, with the exception of C2 (Sonic Cap Gen I).
Back to listening. Fab was a little concerned that the LF of his amplifier design would not come through my powered woofer the Montis. I can tell you that it does. Let's take another recording:
This album was originally supposed to be written by Johan Johansson (sadly, he has passed away), however, creative differences led to a change. Hanz Zimmer and Benjamin Wallfisch provide us with a descending sonic roller-coaster, dropping us from an apex into a sledgehammer of low frequency and power. The Montis excited and resonated my slab home (5,000 sq. ft.) to its core. Oh yes, the USSA-5 does LF! But, this isn't one-note bass. This is articulate mastery of low frequency the likes I've never heard out of my system. This is a PHD of low frequency: tone and emotion are vivid and illuminated. That's what this amp does: it simply illuminates the recording. Wire with gain.
The album finishes with the sweet and supple vocals of Lauren Daigle in Almost Human.
In this track, Lauren gives us enormous vocal range: softly, then soaring to Alto
with tremendous control. The USSA-5 separates her vocals, allowing them to crescendo in the room while still maintaining spectacular separation and timber of accompaniments.
Then I-shifted to Some Great Jazz Reviews another from German: Klaus Doldinger's Best:
Can't say enough about this guys work. Track one: Blues for George.
The USSA-5 allows us to crawl into and take a respite from the world inside of Klaus' saxophone. Piano accompaniments notwithstanding. The USSA-5 foams with clarity, and openness with this album. Touch and emotion abound. You are transported to another time and place, floating in the ether of audio bliss. Oh yeah, this is really a good amplifier.
Compared to my other amplifiers what can I say? The VHEX+ is a class A/B design, with much more power. This amplifier is revealing but nowhere near what the USSA-5 provides. It can drive my panels very well with no strain. But it misses on emotion. The Aleph J is closer in its design and intent: a voltage source, class-a amp by the brilliant Nelson Pass. Nevertheless, it simply cannot compete with Fab's design. At this point it is an older design, better by his newer ideas.
I have never heard any of the other First Watt designs, therefore, I cannot comment on how they compare to the USSA-5.
A little bit about myself. I work at a very short work week, and while at work, I am constantly working at home. I spend a lot of time listening to music. I can afford any amplifier product. But, I have never heard an amp that sounds this good. Yes, there are commercial products that may be good, but you will pay dearly for them. I've been building loudspeakers for 30 years and have started building my own electronics about 10 years ago. I'm not good at it, but i'm learning. I don't buy "snake oil" products: I build everything myself. Sometimes I buy things because it is just frankly easier to do so when a commercial product is better design then I can find out there. Enough about myself.
In closing, the USSA-5 is brilliant engineering: it is a triumph of both emotion and truth.
Isn't that what we are looking for in life?