Strengths: Overall using this amp there is far more detail at low volumes than previous amps I have used. Bass is full and using a 6.1 setup, surround effects are realistic. There are a large number of inputs both for video (Best using the 2 Component, though up-scaling from S-Video sources gives another 4) and audio (3 x Optical (1 Front), 2 x Coaxial). Although there are fewer DSP effects than other manufacturers systems (i.e. Yamaha), this is probably for the best. For movies I only use THX cinema mode. Listening to Mike Oldfield’s Tubular Bells 2003 using both analogue 5.1 (Source A) and DTS+Neo:6 (Digital Coaxial, Source D). By switching between both (A) & (D) whilst playing. I was able to ascertain the following: (A) Provided a richer sound with crystal clear bells and was more realistic. (D) Provided a sound with more noticeable surround sound effects and is noticeably louder and more powerful than analogue. Although this is probably due to the quality of the 5.1 audio leads I'm using. Overall either source has its merits and demerits.
Weaknesses: Something I hadn't consider it is very large (Depth and height) and heavy (21.2Kg), I use an Apollo Aria Modular hi-fi rack (http://www.apollohifi.co.uk/modular.htm). I had to re-assemble the rack around the amp due to its height (188mm). Low audible volume on analogue sources I now use around -20db. On digital I use around -30db for the same audible volume level. Remote is functional though a little bulky and plastic, the remote I have with a Pioneer PDP-434 Plasma is what I expected with nice a metal finish.
Overall: Although I am not an audio expert, I have setup (IMHO) a decent sounding Home Cinema system, using mainly Pioneer, VSX-AX5Ai-S (Amp), DV-668 (DVD), PDP-434HDE (Plasma) on Mission m7s (Speakers) with an Atomic 8.2 sub (6.1 setup).
However to take full advantage of this amp I will be upgrading to the DV-868AVi (DVD) allowing I-Link (1394 firewire) for Digital Audio music. I will also be upgrading the sub.
Personally I think it's more than I needed, as now I will most probably be replacing all but the Plasma. However it has brought more out of the setup I have.
If you already have a budget setup (like me), it's a good upgrade. If you're starting out from scratch (perhaps on a budget) try the next model or so down Pioneer VSX-2014i-S or the 1014i-S.