Whilst the new AV receiver (the Sony STR-DA2400ES) has automatic calibration, it didn't get the levels quite right as far as I was concerned. Not enough centre channel, too much sub and rear effects. With a bit of fettling, I'm now much happier with it - so the moral is to not necessarily blindly trust the microchip, because undoubtedly your ears are better than an algorithm.
My next issue was that I had acquired a very low level hum from the subwoofer. It was never there before with the old amp. With a bit of Googling, I found out that it was most likely a ground loop hum - and this was backed up by the fact that my old amp only had live and neutral wires in the plug (the earth pin was plastic) whereas this new amp has all three pins wired up - essentially this creates one great big circuit around the earth loop, which adversely affects the sensitive audio circuitry. I don't fully understand the physics of it (maybe Olitee will stop by and explain it) but as far as I could tell, the common solution was to wire the ground pin on the back of the amp (usually used to ground record players) to a metallic part of the subwoofer casing.
I went out to Maplins, bought a packet of ring terminals and a couple of metres of thin wire (total cost, £2.38), soldered it together and then sanded the paint off a small portion of the sub's metal backplate. Then I attached the wire between the amp and that part of the sub, and hey presto, no humming. As far as I'm concerned there's some sort of witchcraft going on there, but if it works, I'm happy.
Another bit of fiddling (as I alluded to last time) has been getting this new system to play digital video files successfully. I've discovered that the Blu-Ray player will happily playback my MP4 files that I've encoded with Handbrake, and even better it will also decode the Dolby Digital 5.1 soundtracks from these files as well. However, it will only work with storage attached directly to one of its two USB ports - not over the network (despite the fact that it is connected to it). This has made me hanker after some kind of dedicated solution for playback of video files, because the Blu-Ray interface is, at best, slow and clunky. It works, but it ain't elegant.
This got me thinking about investing in some kind of small Nvidia Ion-based computer to run a combination of Ubuntu and either XBMC or Boxee. Both have their advantages, and having tested both out on my iMac, I can see that this would be a superb solution. However, we're looking at around £200 for a capable computer like the Acer Revo or similar, and when there are a lots of rumours buzzing around about an imminent new AppleTV (allegedly much cheaper than the current one) I would be daft to invest now. I'll hang on.
Finally, I've just found out that Lovefilm have added four hours per month of digital movie streaming to my current package at no extra cost, and rather pleasingly I can use this via the Blu-Ray player. I haven't tried it yet, but I shall report back.