Well they sure
look very similar, and the prices are comparable.
The specs say that the ART has max gain of 70dB (XLR-XLR) vs. 60dB for the dbx unit. Not sure if you'd be happy with either of these units if you have them cranked that hard, though. But if you're using a mic with a relatively low output, it might make a difference.
EIN is listed at -129dBu for the ART vs. -125dBu for the dbx. Doesn't seem like that would make much of a difference.
As for the tube, the ART uses
a 12AX7A, vs. the dbx's 12AX7. I have no clue whether this would make any difference, or even whether they
are different. Both tubes are of Russian manufacture, and both ART and dbx say the tubes are "hand selected", which I assume means that the factory can't afford to buy a machine to do the same thing.
I have
a Tube MP Studio, and I am reasonably happy with it. AFAIK it's the same as the Tube MP, except that it has a VU meter. If you'd like to get an idea of what it sounds like, go to
my NoWhere Radio page, and have a listen to "O Holy Night". The chain is MXL1006 > ART > Audiophile 2496 > ProTools FREE, with minimal processing. Gain settings on the ART were moderate, with both controls near the 12 o'clock position -- I think the input was set slightly left of center, and the output was set slightly right of center. That setting doesn't drive the tube very hard. (No critiques of the recording, please. I know it's not ready for the big time.)
To answer your question: Is there any real difference? Maybe, but probably not a very significant one.
HTH,
Don