Darren,
I have an upgraded Integra Research RDC-7 preamp and IMO the upgrade is a waste of money. It was overpriced at $300 and it would be crazy to pay $500 for it.
THX Ultra 2 is crap, you can play 5.1 sources in 7.1 on your Integra without it and it sounds MUCH BETTER. THX Ultra 2 compresses the sound and reduces the dynamics of the recording.
The sound in both stereo and surround is the same as before the upgrade.
Onkyo is fixing the audio dropouts under warranty, see
www.***************.com for more details.
Razvan