if I really go that hardcore.....
I'd use tube amp with digital connection between amp and computers.....
I don't want to make any argument, but S60 has some issue to quality as audio player
I have been using 6630 and 6680, I found it has issue one phone itself and player software, there's always pop when pressing button, this is annoying, and possibly damage earphone (the pop is like turning on an amplifier, and it happens on AD15 and AD46)
the player software also has problem, both player applications (oggplay and supplied player) are unable to display Chinese, Japanese, Korean id tag correctly
lacking streaming audio capablilty is also an issue, realplayer is dying, and I even don't think it can live over 2008, we need a Symbian developer to pick up TCPMP source code to make it S60 version, this is the only hope to make S60 device as a decent audio/video/streaming player
about a2dp, I have a decent client (use my favorite earphones) that makes sound fine, it's used with laptop (no more cable clutter) and pda (that I don't have to worry to damage the unit when doing workout, just locate the unit secured), I dragged my 6630 down when using treadmill, luckily it survived, then I know the risk with cable