sorry folks, my bad, I meant the RX-V630 should have no trouble handling the 6ohm load of the VP150! Thanks for the quick correction Peter.
Birdman, I'll try and throw down a few thoughts for you on the addition of the external amp. Unfortunately, anything I say has to be taken with a large grain of salt because I did not perform a blind listening test using both setups.
I decided I'd like to try the seperate route last year. After doing lots of investigating, I realized the cheapest way to get into it was to buy a good quality amp and a AV receiver. I got lucky when the Yamaha RX-Vx40 series came on the market, I was able to pick up the 730 for only a couple-hundred dollars. That was the first purchase in the setup. I had it hooked up to the M60tis for about a month before I added the external Sherbourn amp.
To be completely honest with you, I was unable to hear any differences between the receiver and external hookups at lower volumes. At these ambient-medium volumes there was little or no difference between the amps(at least nothing I could remember - since I did not do a direct A/B). The difference I found was at louder volumes - 80-100db. Sure that's extremely loud, but I do like to listen to movies at a high volume. At these levels, the poor Yammie really started to strain. You can see here
that the Yamaha does have a drastic power drop when driving 5 channels. The addition of the Sherbourn really helped out and I think that if you planned on listening at extremely volumes, or have a larger room, seperates are the way to go. You won't see the strain at higher volume levels. That being said, I think the 1400/2400 or the HKs would be more up to the task than my older 730.