Well, late reply. But the Pioneer amp I had was bad. I got rid of it just yesterday. It was a 2 channel 200 watt (40wx2 @ 4ohms powering all four of my speakers). So yeah, not a whole lot of power. And the sound was aweful at around 500hz-2khz, wasnt coming out as it should.
Got an Alpine MRP-F300 and instantly noticed a huge improvement, does a MUCH better job at the low end, bass feels real tight and the 500hz-2khz issue was solved.
As for the head unit, here's my take;
I've tested a lot of head units, this was the first thing I was looking at for a long time before I even bought my car. Before the JVC KD-R900 I had an alpine CDA-117. Great sound quality, absolutely terrible interface, navigation and speed. Connected to an ipod it scrolled through artists and songs extremely slow. Skipping to the next song caused a delay sometimes of up to 2 seconds. USB sticks with music were 'banked' (put into slots) and then sorted somewhat by alphabet. This process took ages to do so, and then a little less when connecting it again. When new music was added to a device, the whole banking/slot issue completely botched the organization, causing a near complete freeze of the head unit. When more than 1,000 sounds were on a device (like USB key) they were then put into a second bank/slot of another 1,000. Basically, the unit uses 20 slots each with 1,000 songs available. When new music after the 1,000 tracks point was added, it was NOT clear which slot had which artists or songs, things got COMPLETELY mixed. At this point, the process for loading new tracks was so incredibly slow, it was almost like having a hard on before *** but the girl telling you shes on the rag, instantly killing any kind of excitement.
The problem with every other unit was worse if not as bad; files on a usb drive or external were displayed not in alphabetical or numerical order, but the order of their creation DATE!
The JVC unit is the ONLY single DIN unit capable of displaying all files and folders in alphabetical/numerical order, its gap between tracks is VERY short, skipping to the next track is almost instant, scrolling through lists of songs or folders is VERY fast.
Sound quality out of the JVC paired with the Alpine F300 amp is very very good (albeit am using Focals, so they do sound a little bright). However, I may have to say the Alpine HU might have been slightly better, but I'd sacrifice a little worse sound for my hair as the alpine was a nightmare to use. Eventually the usb port failed and wouldnt detect/connect to any device.
Those are my 2 cents for now. Am loving the Alpine amp.