What would you upgrade next ??

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.

Mabonn, I have owned many 50K plus sytems over the years, both tube and solid state (my ears are pretty good). I recently added the AV123 supertweeters to my Krell Resolution 2 speakers (musical but not the last word in air and extension). What they do is add smoothness and better articulation across the frequency band, from the lowest lows to the upper most range. Sparkle and air are definately augmented but not in an overt manner..it just sucks you in to the point that trying to remove them causes great sadness! By the way, they use almost 0 volts and come with a superb set of interconnects (I tried to better them but to no avail). Also, if you use the 8ohm taps of your ARC amp directly, bypassing the autoformers, you will illuminate your soundstage and create far more focus...Hell, I used a VT100 on my Watt/Puppy 6's with no problems. The supertweeters were a low cost, completely refundable experiment that payed off big time!!