What would you upgrade next ??

Can I improve the resolving power of my system?

Suppose the real answer to your question was -- NO. Could you deal with it? Is it possible that without replacing virtually every component in your current setup that you won't be able to improve the resolution of your system? I don't know the answer to that question, but I do know you are doing a disservice if you don't at least consider the possibility of answering YES.

Have you tried a really good headset? This might give you the new experience which you seem to seek. The very best headsets show you how far loudspeakers have to go. Not the most convenient, but...

The other thing your system lacks is equalization for room effects. By now everyone knows that I like the Behringer DEQ2496, but its low cost ($350 including mic) may scare you away. So go for a PARC (but it doesn't have a RTA).

If you are amazed at the responses, then consider again what you said in your original post. An emotional connection with the music coming from your speakers is not always so easy to come by. If the sound of your music connects with you on an emotional level then that is really what most of us are about here. (having a system that moves us) I think my suggestion of focusing on your source is, pardon the pun, a "sound" one. If anything, the Arcam may likely be the weak link in your system. From most accounts, your speakers are excellent and ARC gear has a strong following. Take it from someone who has struggled for years attempting to get a system sounding right, you've achieved something significant already. Before you go mucking about with different cables etc., I would shuttle several digital sources through my system head to head against the Arcam (doing A/B comparisons). This is one of the easiest and simplest ways to take your system up a level without losing the synergy that you have now. If none of the players you try clearly outperforms the Arcam then at least you know that it is creating it's own magic in concert with your preamp/amp and speakers. Let me remind you, in system building, synergy can be very elusive. I know of a few guys who started making changes to their setup and the result was, they lost the magic and couldn't restore it. The source is the way to go.

>>The source is the way to go.<<

No that's incorrect.

So are the D/A converter and cable recommendations.

You get more bang for the buck with speakers than any other component.

Sell your speakers, add a couple thousand, and buy a pair (pre-owned) of speakers that knock you out.

Good luck.

Thanks again for all your responses. Here is my reaction to your comments so far:
Some say start at the front end, either a better CDP or an outboard DAC, followed by pre-amp. Audiofeil says no, upgrade the speakers. Say I can get $2500 for my Adagio's and kick in another $2k. Audiofeil, what would you recommend used for ~$4.5K that you think would best the Adagios ?
Others suggest room treatments (no doubt a good suggestion), AC power conditioning, power cords, and isolating the CDP from the AC to the other components. What specific recommendations would anyone recommend for AC conditioning, power cords, and isolating the CDP ??
Dave b suggests adding AV123 supertweeters. I am really intrigued by this suggestion. The Adagios have circular ribbon tweeters that are supposedly flat to 30KHz, and I am 56 yrs old. I think my hearing is pretty good, but I'd be surprized if I can hear beyond 16K. I'd like to hear more from you as to why you think adding a tweeter that extends thehf response from 30K to 50K would add to my listening experience ? The reason I ask is that this upgrade is relatively inexpensive, so it is certainly worth considering.