ARCAM AVR-600 vs. Yamaha RXA-3010 ???

The Arcam is much warmer and more dynamic

I really enjoy mine in my ht setup

For 2 channel performance, the Arcam.

There is one more posibility to consider though. At the price of the Arcam you could keep the Yamaha and use it for center & surround duty only and get an audiophile 2 channel integrated amp with a HOME THEATER BYPASS feature to power the L/R mains for your two channel listening. There are many much more powerful integrateds that will out perform the Arcam AVR at way under the cost of the Arcam - Marantz PM11S3 or PM15S2, McIntosh MA6300, Creek Destiny II, are some to come to mind with direct power amp inputs or Home Theater Bypass.

If I liked the Yamaha for my HT duties but wanted to improve my 2 channel listening, this the way I would go. Good luck in whatever route you go.