I'd first started playing with the idea of using the pre-amps and external amplification with my receiver back with a Denon AVR-3803. While this receiver did very well by itself, I did feel it performed slightly better at higher volumes with a dedicated amp for my mains. Whether this was actual or perceptual is debatable, but with my room size and the volume I preferred to listen to music and movies at times, I felt the change was an improvement. Since my first foray into this type of configuration, I've used an Outlaw 755 200x5, bridged Behringer A500s and a Sunfire Grande Cinema 200x5 (currently in use) for my main system and have never wanted for more power. By no means to I listen at ear-bleeding levels on the norm, there are times I prefer to turn it up and I feel more comfortable knowing the power is there when I want it.
When I changed my Denon out for a Yamaha RX-V2500, I felt the pre-amp stage on the Yamaha was noticeably better. Again, this is subjective and could be placebo effect, but as attached as I was to the Denon, I don't think I was more biased towards the Yamaha. I was (and still am, using it in my secondary system) thrilled with the pre-amp performance of the RX-V2500 on many levels, however I felt its two channel performance could be ever so slightly better.
Out of curiosity, I ordered an Emotiva MMC-1 pre/pro and swapped out my RX-V2500 to see if I could notice any difference in performance. In all honesty, the only improvement I have been able to perceive is with two channel sources, the multichannel source, whether hi-res audio or movie soundtracks, is imperceptible for me. Again, as Chris alluded to, this could be placebo as what I was looking for was better two channel performance, but I think all but the tone deaf would notice a difference. If it weren't for Emotiva's 40% discount on next model pre/pro's, I probably would've sent the MMC-1 back as the Yamaha beats it hands down on features, functionality and holds its own for most of its performance and presentation.
I'm sure the 1014's pre-amp section does a fine job on it's own, but there is a chance you'll notice a difference with a higher quality pre-amp section in either a step up in the Pioneer models, a change to a different manufacturer's receiver with a better performing pre-amp or possibly even a standalone pre/pro. The question is will the difference be enough to justify the change for you. If you haven't done any kind of room acoustic treatment or aren't completely satisfied with your speakers, those two areas will likely make a larger impact on performance than a pre-amp change... -TD
