If want to upgrade the PSU, try this:
Acopian B5G120
I think the rating of this power supply (5v 1.2amps) might be a bit too low. The stock switcher that comes with the Squeezebox is rated at 5v 2amps, so I'd want to get something at least rated that high.
---Gary
Have you measured the SB3's current draw?
I'll bet you haven't, but if it makes you feel better get the 2.1amp B5G210, it's $20. more,
or if you want a lower ripple spec, get the A5MT510, $75. more.
Either way, it's cheaper than a BC or CIA PSU.
Once again, the bigger improvement will be a great DAC, like Mr. Van Alstine's Insight.
IMO, SB3 owners with external DACs should donate their units to a friend, and get a Duet, which has a much better sounding stock digital output, and a wonderful remote.