Why did you choose those two particular DAC's (while there are so many more DAC's out there)?
TabllOs, the Dodson DAC was pretty good in its day, but the Accustic Arts Tube DAC II is in another category all together. Take a look at my review of it here on the GON for more details regarding its reference level performance.
Chris, I have idea way TabIIOs would be interested in the Dodson DAC, but the Accustic Arts makes great sense, ranks up their with other reference pieces, German build quality, and finally can be purchased for a whole lot less then other reference DACS.
I have the original 218 (didn't even know the Palladium came out), use it every day for CD, DVD, iPod (through Wadia iTransport) and it is a superb DAC. Haven't heard the AA, but I have found nothing about the Dodson to be dissatisfied with, which is saying a lot for an obsessive audiophile. Just because the AA design may be newer does not mean it is better -- or not better.
If you're still pondering the choice between Dodson 218 and Accustic Arts DAC II, you might want to read this thread that started yesterday in the Misc Audio forum:
Jeff Smith of Silversmith Audio in the San Diego area will service Dodson 217 and 218 DACs without regard to where they were bought. I know, because he did work on my 217 MKII that was bought on Audiogon from a professional re-seller. Jeff never asked where I bought it.
I have seen at least one ad for a Dodson 217 MK II on Audiogon suggesting that a buyer could have it upgraded to a 218. According to Jeff Smith, the 217 MKII cannot be upgraded all the way to the 218 level. He does offer a software upgrade that I believe is the same software run on the 218, but there are certain parts and/or circuitry in the 218 that cannot be duplicated without substantially re-designing the 217. My unit was upgraded as much as it could be toward a 218. If you want more details as to the difference between the upgraded 217 MKII and the 218, I suggest you contact Jeff. I found him helpful and easy to deal with.