Pros: For music lovers more than for sound lovers. Built to last forever and survive technological changes.
Cons: Don't know what to say
I listen to classical music, jazz, pop, old jazz bands, great historical recordings from labels DECCA, CHANDOS, TELARC, NAXOS, PHILIPS, CHESKY. I regularely go to concert (classical). My "ideal" system would be portable and reproduce the sensations I have in a concert room.
I will first describe my own system and the "why" of each element.
First a MacBook Pro with more than 1.5TB of high definition music (24bits, mostly with 96KHz but also 44, 48 88, 192..). The music comes from Qobuz, a french company with a wondeful service. With a $200 annual subscription, you get access to a huge catalog of discounted high-res music, with regular promo that add even more discounts. You also get high-res streaming, and iPad/iPhone apps. (yes, I want to help them because they provide treasures at a low price and they are desperately in need for new customers to survive). I feel it is like buying master paintings for an incredibliy low price instead of having reproductions...
After testing several bit perfect applications for the Mac, I chose PureMusic, the more "analogical" in my opinion.
Then a "totaldac d1" USB cable, considered as a top contender, designed by a guy who works with his ears and designs some of the best DAC available, unfortunately these one are out of reach for me.
Then the DAC: I chose the Resonessence HERUS plus. Few words about this one, chosen after testing few other DACs: it is unbelievely powerful for what is basically a dongle: music flows with weight, details, and a very good imaging. It is very close to a CHORD Hugo, the CHORD bringing even more details at the cost of substance: i find the Herus with more body and impact than the CHORD and since it is much cheaper, I chose the HERUS. The same remarks apply to the CHORD MOJO. Then my beloved EarSonics Velvet IEM: this one has everything, I will qualify it as the "grand" sound IEM (40 ohms).
Let's speak a bit about the HERUS. I ordered my HERUS at the same time I ordered the TU-05, except that I got my HERUS three months before my TU-05. Three months during which I tried to figure out why I had ordered an additional amplifier less powerful than the HERUS itself, since the HERUS was delivering almost everything that I was expecting. So basically, what could add the TU-05 except distorsion since the source was already extremely satisfying to my ear ?
Then I received my TU-05, number #63... I will not describe the beauty of this little thing, some already did it much better than I could, and the pictures from Shikada san on facebook already give a very good idea.
I bought a short audioquest "big sur" cable to connect it to the HERUS.
With hundred of hours of HERUS music in my ears, I pluged-in the new TU-05.
So, is there microphonics from original tubes? mmmmh, maybe a very very small effect if you ping the amplifier with your nail, but you have to listen hard. The amplifier is silent: no noise. The original tubes are 1U4 Raytheon from the US Army and 3S4 from General Electrics. The amplifier comes with a small 100-240V charger, 9V 1.3A. Charging takes about 8 hours.
The sound was very different from the HERUS alone, with a sense of immediacy, a little less details, or better say, better integrated details: you do not "hear" the details, they are just there, flowing with the music. With the HERUS alone, I use to think "this is great, I can hear a strong echo, the room must be large and reverberant", with the TU-05, you just FEEL in a big room, the echo is integrated with the musical message. It is also more natural, more "analogic"... no, in fact, it is "fully" analogic: there is not one ounce of digital or electronic in this sound. The sound is less analytical than with HERUS alone, and it has a lot of flesh. The space is not wider, it is just more believable. The sound is not more transparent, but it is definitely much closer to what I can hear in a concert room. It is also very refined, particularely with human voices and violins/cello: we get one or two levels up from an "excellent reproduction" to a "natural reproduction", where words have less meaning than physical sensations and feelings. It is strange to try to analyze what you hear with this amplifier, because the words usually used to describe an amplifier lose their meaning: sibilance, distorsion, timbres, dynamic, decay... with a source as perfectly recorded as possible, a good DAC with details, and a TU-05, I believe the result can be very very close to the original experience.
So yes, the TU-05 adds pure beauty to music, urging the need to spend even more time listening to music. Old recordings, those recorded with vacuum tubes equipment, get a new life.
I use rating stars in iTunes because, with 2000+ albums, some kind of classification is needed. With the TU-05, I am adding one star to every single album, because even "so-so records" are much much more interesting through the TU-05!
Bass: using "Pure Music" on a mac, it gets access to built-in plugins, one of them being a very precise equalizer. I know, it is not very "audiophilic", but by adding few dB at 20Hz, 25Hz, 31.5Hz and 40Hz I think I get 30Hz flat. The TU-05 will not go much lower, while the HERUS would. Anyway, at no time did I feel I was in need for more bass, there is already plentyful. Maybe I will switch tubes later for experiment.
Just close your eyes and listen: this TU-05 is damn good at making you feel you are listening to the real thing! a fantastic experience of music immersion.