I own the Granite 657 CD player. Personally, I think it's fantastic. The CD players I have always ranked at the top were the Audio Aero Capitole, the Electrocompaniet, and the high drawer YBA. I haven't heard the YBA in more than five years, so let's scratch that one for now. And, I was never able to compare the Capitole to the Granite.
I have A/B'd the 657 against an Electrocompaniet, and while after getting my bearings, the two were a bit different sounding. In the end, I preferred the extra warmth and weight the Granite provided, though I think this will come down to a question of personal tastes and system leanings. The Granite did have the low frequency advantage, which more than surprised me. But, they were both Grade A players.
I do believe that running the Granite CD direct would have allowed it to put some distance between it and the Electrocompaniet, but most people run a preamp. In my experience, running sans preamp offers significant advantages in openness, naturalness, clarity, dynamics, slam, and bass - not to mention the cost savings.
The other unique feature regarding the Granite is that there is a second set of outputs, which is the Granite 650 solid state fixed output CD player. It's really a very interesting proposition. The solid state output is a bit mellower, with bass that sounds to have more extension, impact, and oomph. I use this with a pair of variable attenuators straight into my AtmaSphere monos. The variable output tube 657 adds some sheen and liveliness to things, and an overall beautiful sound. Which do I prefer? Well, the nice thing is that I often switch between the two, depending on my mood, the music, etc.
In playing some of my SACDs on my Samsung HD841 Universal player in comparison, there are definitely elements to the SACD that are superior to me over the Granite 657. For instance, on the Sonny Rollins "Way Out West" SACD, I can hear both the body and strings of upright bass in such a combination that I have never heard through the Granite. The Granite does a better job with the midrange, vocals, and detail, in addition to providing a relaxed sound. If you asked me to choose, as the SACD format is not so well entrenched, it would be the Granite 657 in a heartbeat.
In your situation, Barrelchief, I very much concur with Kitdog. Do I think the Granite 657 is better than the EC? Yes, I think so. I also very much love the variable output. But, the EC is a dynamite player, as good as things get. Were you to own no CD player, and asked for my recommendation, I would pick the Granite over the Electrocompaniet. But, since you already own the EC, I think I'd just stand pat. The difference probably isn't worth the effort.
A final consideration is that finding a used Granite 657 is certainly not an easy feat. You VERY rarely find them here on Audiogon. And, no, mine is definitely not for sale. For anyone interested, I suggest you talk to my friend Steve Monte at Quest For Sound - dynamite player, dynamite dealer.