Quote Originally Posted by blackraven View Post
Anjani, the SDS-470 is basically 2x254's in one chassi. I would go for the 470 just for the added power and dynamics. You never know what speakers you may end up with in the future. The added power may come in handy.

I just place the Parasound back in the loop and it definetly has a more musical, warmer midrange with more depth but it is not as transparent. It's a trade off. I like both amps. I still prefer the A21 but there are many things I prefer about the CDA-254. I think at the prices that the Class D amps are being offerred it is a no brainer. And pairing them with a tube pre will certainly improve the midrange. I am I going to buy a Little Dot MKIII tube preamp to try with the amp. My son's Maverick Tube pre certainly warms up the midrange. I think the Little Dot with 4 tubes will be better than the Maverick with one tube.
I got a reply from Tom:

The 470 is able to drive tougher loads even down to 2 ohms. I would recommend the SDS-470. It’s pretty hard to best right now. The sonic quality is really about the same. Both excellent!
So looks like I'll be getting a 470.

Note: I was wrong about the prices - the 258 complete amp is $565 while the 470 is $590, so the 470 is slightly more expensive (I think the 470 model I saw that is cheaper than the 258, did not include a transformer - which is why it is cheaper)...