I have a Pioneer 656a ( I am in the UK) and I want to purchase the Doors Perception box set, however, I have read that Pioneers have trouble with the DVD A on this title. Can any of you guys comment on this?
I really want to hear this set in surround.

Hi Morecambe. Welcome to the forum. I did a firmware upgrade myself on one of my 563a units. I found the upgrade online. Your 656a resembles the 563a, but I'm unsure if it's the same upgrade you would need. Perhaps someone else can answer your question better, as I have little knowledge of your specific unit.

Older Pioneer DV565 (AKA the 563 in the USA) as well as certain versions of the Uk DV568 cannot recognize any disc authored with the industry-standard MEI tool (Panasonic/Matsushita, aka Sonic's DVD-Audio Creator as well) from the spec change where the book went from 1.0 to 1.1
A firmware update fixes the DV565.
The DV568 did not have the initial problem, but it did have new problems that were not present on the 563 - it seems the update fixed some issues but broke others.

The 656 is an unknown item to me, but as the whole world knows the Pioneer spec implementations are a tad on the eccentric side. I would still guess you will be okay though. It's a great box set....