If money is not a concern, you may want to take a step back and reevaluate where you're at and where you want to be. Don't get stuck on what you have currently, look around, don't limit yourself. I'm highly skeptical of mods, personally, so will leave that matter to others, though I do have more then my fair share of cdp/sacdp/dac experience to offer, if you'd like to hear it.
Personally, having owned the Sony (ho-hum) and the MF dac (great with a great transport), I'd say, if you have the money and desire to approach SOTA sound for around $3-4K (used), toss the Sony and the A324 dac and buy the Esoteric DV50. Alternatively, trade in your A324 dac towards the crazy good Trivisat 21 Dac and connect it to a Marantz DV8400 if you must keep a SACD/DVD player as a transport, which I'm told by a few friends with great dacs (Chord64, Electrocomapnient, Kora and the MF21 dac) that it is a very good transport, better then any other DVD based player they have heard (many) and competitive with dedicated transports under $2k. That's all hearsay, so don't hold me to it, but you can find other accounts of the 8400 being a solid transport in the AA archives, if that helps.
That all said, I personally grew very annoyed with the SACD software situation, sold my SACD players and have been playing with Wadia's, Cary's, Consonance and upper end Musical Fidelity CDP's lately in the same ~$2k price range as the better SACD players (talking used here, mostly). No suprise here, the redbook from the CD only machines is quite a bit better overall. Now, don't get me wrong; I love SACD sound, it's a significant upgrade over redbook, but I have only ~50 sacd's, of which I play less then a dozen with any frequency, yet have countless hundreds of CD's and all of the new music I enjoy have little prayer of ever hitting SACD, so a good cd player just made more sense to me....
Personally, having owned the Sony (ho-hum) and the MF dac (great with a great transport), I'd say, if you have the money and desire to approach SOTA sound for around $3-4K (used), toss the Sony and the A324 dac and buy the Esoteric DV50. Alternatively, trade in your A324 dac towards the crazy good Trivisat 21 Dac and connect it to a Marantz DV8400 if you must keep a SACD/DVD player as a transport, which I'm told by a few friends with great dacs (Chord64, Electrocomapnient, Kora and the MF21 dac) that it is a very good transport, better then any other DVD based player they have heard (many) and competitive with dedicated transports under $2k. That's all hearsay, so don't hold me to it, but you can find other accounts of the 8400 being a solid transport in the AA archives, if that helps.
That all said, I personally grew very annoyed with the SACD software situation, sold my SACD players and have been playing with Wadia's, Cary's, Consonance and upper end Musical Fidelity CDP's lately in the same ~$2k price range as the better SACD players (talking used here, mostly). No suprise here, the redbook from the CD only machines is quite a bit better overall. Now, don't get me wrong; I love SACD sound, it's a significant upgrade over redbook, but I have only ~50 sacd's, of which I play less then a dozen with any frequency, yet have countless hundreds of CD's and all of the new music I enjoy have little prayer of ever hitting SACD, so a good cd player just made more sense to me....