You may already have reached a final decision about the purchase of the Dynaco tube CD player, but as the owner of a CDV-2, I figured I would offer my two cents' worth to the thread. First off, it's useful to know that Dynaco actually made 3 versions of their tube player: the CDV-1, the CDV-2, and the CDV-PRO. I am not a technical expert so I'm afraid I can't give you details on the design schematics of these players, or how they differ. The consensus on these models seems to be that the CDV-1 had some flaws that were corrected in the CDV-2, and the CDV-PRO was a further refinement that included the ability to play SACDs. The CDV-PRO has also been given additional upgrades by audio enthusiasts who have published their modifications online. From what I understand, however, the CDV-PRO models are so rare that they are almost impossible to find, and the CDV-1 models are probably not a wise expenditure of your money. The CDV-2 model was considered a decent player when it was released around 1995, and offered the benefits of tube sound -- which could help smooth out some of the sharp edges of digital audio and solid state electronics -- as well as the ability to act as a preamplifier with a volume control, that could directly feed a power amp, or actively powered speakers. These advantages were valuable to me at the time I bought my Dynaco tube player (some 10 years ago, when they were already out-of-production) but as others in this thread have suggested, today it's likely that you could find a better performing CD player for a lower price.
Having said that, I will also admit that tube components definitely have a seductive quality that can sometimes be hard to resist. Owners of the Dynaco CDV players often rave about how superb they are, but for a more objective opinion, there is a 1997 listening evaluation of the CDV-2 by Tom Lyle, a reviewer for Sensible Sound magazine, that is available online. [I'd be glad to include a precise link to the review but, I am only a newbie on this forum and I don't yet have that ability.] From direct personal experience with this model, I agree completely with his basic conclusions: the CDV-2 does a fine job reproducing smaller musical groups, but it does have a tendency to sound somewhat thick or congested when playing large orchestral ensembles. I believe this is due to the stock tubes used in the player, which, as "zx" has mentioned here in this thread, are not the sweetest valves available. Unfortunately I am not an expert in tube rolling, either, so I can't offer much advice concerning replacement valves that might be able to correct this "congestion" problem. However, this player could be worth the investment to you if you had an enthusiasm for finding just the right tubes...
So for my perspective on the Dynaco CD player, here is the bottom line:
Verify which model is being sold.
Avoid the CDV-1
If a CDV-PRO model is available in excellent working condition at a fair price, you may be reasonably inclined to click the "buy" button, even while the player is not quite state-of-the-art by today's standards.
If you're considering the purchase of a CDV-2, weigh your desires to own this piece of tube history against the pros and cons inherent with this model.
Hope this helps.