Upgrading my system. Need help deciding between receiver+amp or pre/pro+amp.

[EddieLarkin]

I'm currently running a 5.1 system from an Onkyo SR509. The lot cost me about £600. I am looking to upgrade to a 7.1 set up, with either a receiver+power amp, or a pre/pro+power amp(s), with a budget of about £2500. Obviously I'll be getting new speakers and a sub (thinking of spending an additional £3500 approx), but I'll decide on that later. Right now, I need help deciding on what my amps/processors are going to be, and whether or not to get a true separate system or a decent receiver and a power amp for the front channels.

Please bare in mind that this will be my first high end sound system and I'm a complete beginner when it comes to this level of audiophilia. So if any of my post seems really newbish please forgive me.

After having a quick look around the web, I came across a very well reviewed separates system. The Marantz AV7005 pre/pro + the Marantz MM8003 8 ch power amp. This would appear to do everything I want, and certainly looks nice, but would set me back well over £3k. What I feel I need the most help with is the price issue. This is a very highly recommended set, but for 3k seems a bit expensive. Or at least the amp does. From Emotiva in the US, I could an XPA-5 and an XPA-3 together for around £900 (before international delivery). The MM8003 costs closer to £1600. And going by the wattage ratings at least, the Emotiva amps appear to offer a lot more than the MM8003.

So, any ideas on a nice pre/pro + amp combo for around £2500? Or perhaps one with several amps. I hear this a decent option, that a 7+ ch amp is going to have too much to do and sound quality would suffer. If this is the case and two or three amps would work better, I'd be willing to go up to maybe £3000-3500.
Also, I would need the processor to be HDMI 1.4 as my set is 3D. Audyssey MultEQ would be nice as well.

The other option then, would be a receiver and a single amp, with the amp being used for the front channels, and the receiver handling the surrounds. This obviously would be a much cheaper option. Any opinions on the difference in quality I'd experience if I did go with this option? I could get a 7.1 HDMI 1.4 receiver with other bells and whistles, plus a 3/5 ch amp for around £2000 easy. I would prefer something with XLR for the pre-outs though, and not many receivers seem to offer this.

Thanks in advance!