I was thinking of building a headphone amp based on a circuit like the one on which the Bravo V2 is based. Being kind of lazy, I just bought this version of the Bravo V2, instead. I'm comparing mine to an original version Objective 2 amp, which I built up from a PCB I got directly from NwAvGuy.
So, what do I think of this Bravo V2?
1) Its output impedance is too high. It loads down trying to drive my Fostex T50RP headphones with 60 ohm impedance. Driving those 'phones, the Bravo gets 'gnashy' sounding. Harsh highs, rubbery bass. It sounds kind of 'electronic.' However, driving my Sennheiser/Massdrop HD6XX 300 ohm headphones, the sound from the amp becomes acceptable. It's still a bit more harsh and electronic sounding than if I use the O2 instead. But at least it sounds on par with a typical PC laptop's headphone output when driving higher impedance headphones. That's a pathetically low bar to clear...
2) I'm not having any noise or channel imbalance problems. Mine seems good.
3) I expected the Bravo to sound mushy and 'tube-y.' Instead it sounds 'harsh,' even when driving high impedance headphones. I haven't tried any different 12AU7 tubes in it, which I will do. But unless the supplied Chinese-made 12AU7 is an utter piece of crap, I don't expect a different version 12AU7 will fundamentally alter the annoying sonic character of this amp.
I figure the amp is worth the cost of its constituent parts. At some point I'll try some of the mods people have suggested. But if you're shopping for a 'keeper' of a headphone amp, ignore this.
I'm still happy with my O2, so if an Objective 2 comes up as a drop again, I'd recommend that. This Bravo V2 doesn't sound anywhere near as good as the O2. Not even close. Sorry.