Well, in all the time I have had the PB-2 I never even considered using dummy adapters in buffer position . Until now obviously.....
I use my DB-2/PB-2 mainly as my high quality portable/transportable rig with my ES5's balanced. I have used balanced D7000's and LCD2's at home but prefer the fuller more powerful HifiMan EF-5 for my full sized cans. With the ES5's this sounds considerably more transparent/coherent. More testing is required but my initial thoughts are to leave the dummy adapters in buffer positions and just take some stacked (8 off) BUF634AU's with me when on vacation to use with full sized cans on the evenings.
The other thing which has pleased me no end is without buffers the ADA4610-2BRZ doesn't make that scarey thud/screech when turning of the PB-2. This used to worry me a lot.
Thanks for the heads up Mike, I'm enjoying the PB-2 more than ever!