Hi guys. My Yamamoto HA-03 just arrived a few days ago. I ordered it from Atelier Audio the Yamamoto dealer in Canada. My order was placed on February 13 and I got my amp on April 5th so about 7 weeks all told. This is my first real dedicated headphone amp up until now I have been using vintage receivers and some small chinese hybrid amps with good results (Pioneer sx737 was my main) Anyway I have only had it a couple days but already I am pretty impressed with the sound quality. I would say this amp is a little warmer and slightly less excitable than my old amp, not quite as lean and mean so I had to pair it with a little brighter sounding tubes in my phono stage to make up for that aspect. I mainly listen to heavy metal so I need a little brightness and speed and a lean tight bass with good control plus a forward midrange doesn't hurt. I am not sure if the Yamamoto has the kind of aggressive attack I am looking for on certain kinds of heavy metal but it certainly has a beautiful way of it's own.
What I do notice is how natural and authentic everything sounds on this amp and also how revealing it is of my source gear. I can easily tell when changing my phono stage, cartridge, tonearm, table etc. like never before. I am sensing a little more detail here and there and the amp is very quiet in terms of not picking up any kind of hum or buzz. The c3m tubes are a tiny bit microphonic so it's good to keep it on a stable surface. Not a problem if you are not bumping or tapping it all the time.
When I first started the amp it actually sounded rather plain and laid back but after running in for several hours it started to open up and get richer in the mids and a more musical timing. I think it still needs some hours of burn in to reach it's full potential. I am also trying to get adjusted to the slightly different sound signature that I am not really accustomed to. Treble has a nice shimmering quality kind of like a moving coil phono cart can bring out. Midrange is great with vocals sounding very natural and electric guitars have good amount of texture and seperate from the mix well. Drums are getting pretty snappy as it burns in. I might have to play around with my gear a bit to try and figure out what works best with this amp. It's hard to say at this point whether this will become my new standard or if I go running back to my vintage gear. Build quality and finish is impeccable on this amp and it's got some weight to it. The Wooden volume dial is a nice touch.
The amp seems to be able to power most of my headphones pretty easily to a nice listening volume at about 1/4 to 1/3 of the volume dial. The AKG K1000 take a little more closer to half of the volume dial. My ESM 4 speakers are only 86.6db efficient but I find this amp can get me enough volume at about 3/4 of the dial to fill my bedroom with sound. Pretty neat trick for a little over 1 Watt of output power at the speaker taps. I would say it's pretty near half the power of my 40 watt Pioneer which is pretty good considering I never go over 1/4 to 1/2 on the dial on that for any headphones or speakers. So you could think of it as having the range of a 20 Watt vintage solid state amp.
Well not much more to say at the moment. I will do some more testing later but now it's time to enjoy the music!
Here are a few photos:Edited by realstar - 4/7/13 at 11:10pm