sony x707es questions

I have a x707es player and would like to better it. From what I've read it is a decent player. My options would be
1- sell and upgrade alltogether? probably coslty.
2-use as transport only and get a dac, I could use some advice on what dac would pair well with the sony and be an improvement over the onboard dac. Would need to find dac with volume control as I run direct to welbone labs drd300b amps
3-mod the cdp as well as run dac, this would probably be the ultimate for this particular player as far as improvement. I have contacted APL they will not mod my machine at the moment they are to busy, so this may not actually be an option.
Any insight/info would be appreciated Tahnx