Yes, I built it last summer (the 6N1P version). As for comparing it to other tube amps, I can't really, since I haven't heard any.
Furthermore, I suspect that mine is not functioning as well as it can due to a poor potentiometer. I was unable to find a store in Vancouver that sold good pots (eg. Alps or Noble) so I had to settle for some cheap one. The thing is really crappy. The left channel is noticeably louder than the right, and I have to turn up the volume pretty loud before the right channel kicks in. Also, the sound from one channel gets partially mixed into the other. Actually, I only noticed this a few hours ago while setting up my new Art DI/O. The reason I am sure of this is because even when I have only one channel plugged into the amp, I can still hear sound out of bother of them. This is more of a problem with one side than other (i don't remember which one).
Putting the issue of the pot aside, I'd say the amp sounds pretty good. The sound itself is quite warm, and detailed. I can hear parts of songs I had no idea existed. I'd also say that it's reasonably fast. I haven't noticed any piece of music that it has had a lot of trouble with.
Now the complaints...
The biggest thing I don't like about this amp is that the sound is too closed in. It doesn't sound as "big" as I would like. I think I might add some crossfeed circuit (or a seperate unit) to try to compensate for this though. The other thing is that I can't stand listening to some pieces anymore because of the flaws I can hear in bad recordings, but this is not really a problem, rather just that it is very revealing.
But I think the amp could sound much better (given the poor pot and refinements suggested). I'll have some time in a few weeks and I think I'll try to find another pot for the amp (Lee's electronics sells the blue alps pots but the 100K ohm ones are on backorder). I'd also like to make the modifications suggested. I hope a final version of the 6N1P version is available soon.
I apologize for not being able to give a better review...it's been almost a year and I've gotten used to the sound and I can't really remember what it used to sound like. But I think the Morgan Jones design is very promising, and a good choice. If you haven't built a headphone amp before, it's pretty easy. You shouldn't have any problems so long as you have a basic understanding and can solder (or don't mind second degree burns and being electrocuted if you're careless like me).
