I can highly recommend the PA2V2...it should drive your Senns just fine. I can't comment on the Shellbrook Super Mini Moy (I assume you are purchasing this used, since the most recent Shellbrook Labs lineup consists of: Mini-Head (and Mini-Head Signature), and the Maxi-Head (and Maxi-head Signature). The Super Mini-Moy was replaced by the amp I currently own; the Mini-Head Signature.
I personally, prefer the sound of my Mini-Head Sig, over the PA2, with certain source material, and with higher bit-rate downloads. I have also found, however, that the PA2V2 sounds better than the Shellbrook, when it's run directly from it's rechargeable batteries.
My Shellbrook only surpasses my PA2V2, when it's run from an AC mains outlet. There is a huge diff in longevity of battery life, between charges. The PA2 will run roughly a month between charges; the Shellbrook only gets about 8-10 hours.
If your priority is detail resolution; I'd say get a Shellbrook. I also have a non-Signature Mini-Head (a limited model, that came finished in black, with silver edges, and a silver volume knob). It also sounds slightly more open and tighter in the bass with great bottom end extension, than the PA2V2, and runs off a 9-volt NIMH batt. (I currently use Maha super-powerful rechargeable batts).
As much as I like the sound, though, of the Shellbrook amps; I prefer the PA2V2, when I go portable, and take it on the road. It's got great bass, clear mids, smooth trebel, and a lifetime no-fault warrenty. You just can't beat 100-hours between charges, and the small sacrifice in detail resolution, is surpassed by the fact that I don't worry about the thing running out of juice; even when I run it hard. A great-sounding execution of design that works!
