CAL Alpha DAC: Stock vs. 24/96 upgrade

I think the mullards have very smooth mids and really clean, crisp highs. Telefunkens seem to get a little better bass. In my experiences, 5751's rock a little better. They do not smooth over any sound. 5751's can handle more plate voltage which is why the can "crank" a little more. CJ pre-amps always came with 5751's and I hated it. They would cook mullards but I felt they sounded a little more "tubey" with mullards in them (I've had a PV-5, PV-9 & PV-10).

Yes, I tried the Mullards in both Alphas with very pleasing results. If I had 3 sets, all my Dacs would have them. The Telefunkens and Mazdas have more air in the highs but the Mullards vocals are crystal clear (most of my music is vocal and acoustic). I have not heard modified players compared to the Alpha but saying they "crush" the Alpha may be pushing it. The Alpha is very hard to beat for the money. Plus with the next wave of audio being music server based, a nice tube DAC will come in handy. My neighbor already uses his SigmaII with an AppleTV in a 2 channel set up with Dali Helicon 400s and a Prima Luna Dialoge integrated. WOW! Both audio and video are outstanding. Plus the simplicity of a music library at your finger tips. I am planning on that next leap with my systems (which is why I have 3 Alphas).

Buda, When I read your posts you sure do make a case for the Alpha. As stated before, I'm still getting used to it. It really does have some characteristics I like a lot. I also own a CAL Icon Mk.II Powerboss which I really like too. Of course, I'm finding it's a different animal than the Delta/Alpha combo. I will probably tube roll before I decide on the 24/96 upgrade. I don't want to spend too much on tubes but it would be a good idea to at least try some out. Thanks for your help.
Kevin

I tried the Mullard's and didn't like it. Very syrupy, lacking in details. The Sylvania 5751's, though, provide a very clean, full, airy sound that was a revelation. I agree with the idea of playing with tubes before you throw down $500 for an upgrade that you will never be able to recover.

Kevin, When you take the cover off of the Alpha, there is the large metal piece/part inside. This is the transformer and is noticeably the most heavy part in the case. It is tall, comes about 1" short of where the top cover would be if the cover were back on. You should use a piece of styrofoam or even better a softer foam. This should be thicker than the space between the top of the transformer and the cover when it is put back on. This piece will then compress with the cover installed and hold the transformer in place to prevent its heavy wait from receiving shipping impact. Since the cover slides on it is fairly easy to do this.

What is known to happen without this is during shipping the box and components takes some real impacts when it is being tossed around and dropped. Due to the weight of the transformer these impacts cause cracks or total breaks to occur at the contacts or base of the piece.

If you ship the piece, you should always do this, but you also need to let the buyer know to remove it before playing. Many people don't know to do this and this is why so many of these units have been sold in good working condition, only to arrive not working at all - no power. I will check my office computer to see if I have a photo of this.