I've had my JMT Altoid CHA-47 - pretty much a stock JMT Altoid, I'd guess - for about two weeks now and I am extremely pleased with it. JMT optimized my amp for Ety ER-4S (I am using the 4P > 4S apadter cable from Fixup). I thought it sounded great right out of the box. There was a tad of brightness present in a few things at the beginning, but after burn-in that quickly receded and I find the amp gorgeously smooth and punchy. Is that a contradiction in terms? Perhaps, but my point is that JMT - and the CHA-47 designers - got the balance just right, in my opinion.
I am mainly running this amp on various portables - Sharp SR50 MD recorder (I know, I know, no dedicated line out on this, but before you jump all over me, I just want to say that the late, lamented Sharp SR- series sound better to me than any Sony's with a line out. Don't understand why that is, but it's true), my HHB Pro MD recorder, a Sony D-EJ721 PCDP (bought it cheap at Target and find it to be so-so, despite its fine line out reputation). Also, for fun, hooked up the JMT amp to my Pioneer Elite PD-65 CD deck and my Sony MDS-JA55ES MD decks. The JMT amp really brings out the best in everything I've tried.
The biggest and quite unexpected surprise to me was how good my AKG K280's sound with this amp. I've had them for around 5 years and never found them very satisfactory. However, they really sing with the JMT amp. Never thought I would be using these AKG's at all, but I'm happy to say that they are getting regular use now (not as much as the Ety's, though).
I also noticed a similar thing about the ultra wide soundstage and separation when I first got the Altoid amp. Don't know if this effect quickly grew more subtle or that I quickly got used to it, but it isn't a problem to me. Interestingly, this effect was much more noticeable on the AKG's than with the Ety's. As I said, this amp was optimized for Ety's - the AKG's were never mentioned to JMT - but, man, those AKG's sure sound sweet with this amp.
Lack of crossfeed doesn't bother me. I've never heard a crossfeed circuit that I liked, but then I haven't heard them all. I would be curious, though, to know what JMT's crossfeed circuits sound like.
I am so impressed with this little amp. The Ety ER-4S and a JMT CHA-47 ... if you can get better sound for the cost of these two, well, actually, you can't.
Thanks again, Jon, for your kindness and skills. I STRONGLY recommend that everyone who hasn't heard a JMT-built amp get one!
BTW, I enjoyed the wintergreen mints so much I went out and bought another tin of them - mints, no amp inside, unfortunately - a couple days later. And then again a few days after that. Wonder how many other people JMT has unknowingly hooked on Altoid mints? The Altoid company should pay him a consultant's fee, I think.
And now that I have a growing collection of empty tins, perhaps I should dust off my dormant (and admittedly rudimentary) soldering skills and start trying to build some amps on my own.
