Not as far as I'm aware. Speak to Brent at Audioupgrades if you're interested, but it'll obviously invalidate your Yamaha warranty, although I was happy to take the chance as they're pretty reliable beasts. On my system the improvements are well worth it. For example, my Proac's bass sounded a bit flabby with the old opamps, so when listening to stereo music I used to avoid Pure Direct so I could let the sub deal with the low frequencies below 60Hz. Since the opamp upgrade, I'm able to use Pure Direct mode as the bass has tightened. It's not just the bass though, the whole frequency spectrum has improved. I also upgraded the opamps in my DacMagic, again a massive leap in performance. Opamp upgrades certainly seem to give quite a large imporvement considering their relatively modest cost. For Yamaha to have included LM4562's in the Z7 would have probably added about £50 to the cost, but I guess that would have brought the sound a bit too close to the Z11!