First off, I am very thankful to have been part of the loaner tour on this combo. A big thanks to shotgunshane for offering his gear to members for demo.
I'll get right to some impressions (some good, some not so good).
Rhapsodio 2v1:
I heard things fairly similarly to much of what has been said here in many regards. But contrary to someone else's comments (can't recall who it was), did not find bass thin at all. In fact that aspect was quite pleasing and deeply extended, with great reach and weight to the sub bass. It didn't cloud the mids in the least.
I found the midrange a bit sucked back (but not terribly V-shaped), and it seemed to have a thin feel to it. It just didn't sound natural to me, and vocals in particular had something of a weirdly stretched, sort of lifeless sound. By comparison the highs were quite extended and detailed, very quick and agile... but were strident with a lot of music. That would keep me from listening at any sort of an enjoyable volume. In contrast I have no problem enjoying my TG334's at any volume, and the highs there don't get piercing at all, unless it's hugely present in recorded material.
Spaciousness is also another area I felt the 2v1's struggled. They struck me as more limited to the ears, and didn't really project 'out-of-head' at all. Going back to the 334's everything is more spacious, with better specific instrument placement and layering. This helps with more of a 3D sensation after the 2v1's.
So with the midrange tone/recession/thinness, constrained spatial presentation, and treble bite, in all honesty I didn't find the 2v1's a good match for me. But if someone is searching for a very dynamic (very extended at the top and bottom frequencies), with awesome detail and speed, then these could definitely be the ticket!
Shozy px-m1:
Unfortunately a bout of travel has kept me from doing a whole lot of experimenting with the amp, but during the time I did get to listen I noticed it helped the 2v1's harshness issues nicely. The amp drove the RDB's easily on low gain. Sonically, it really helped open up the space, and took a bit of the edge off the highs. Bass also got more controlled. The form factor is very nice, and highly pocketable. With the TG334's, the effect was not as desirable. It took some of the treble sparkle away from the Fitears, and that is not welcome when I find the highs pretty good as is straight out of the Sony F807. But it sure helped the treble bite of the 2v1's.
I would have liked to have more time to experiment with my orthos but they're in storage for a bit currently and my listening has to be done on IEMs. But with other comments here, I imagine it does a commendable job with most headphones.
Again, thanks for the chance to demo this gear.