What's wrong with my Cal Delta/Sigma?

Hissing -- Most likely the tube needs replaced.

I used AudioQuest power cords with the Ferrite removed...

I have an Alpha/Delta combo, and I just replaced the tubes with 1963 GE large plates. This has opened up my soundstage immensly. Also, the analog cables and the powercord are custom made by a guy on ebay. Do a search for Cableplex. The Nirvana cables are the best I've heard, they beat out a pair of $400 straightwires, for only $75 per 1 meter pair. His powercords are top notch, both the alpha and the delta have one. As far as the digital cable, I contacted CAL, and they told me their perferred method is the digital coax. I have two that I perfer, one is the ZuCable Firemine and the other is a custom cableplex. I can hardly tell the difference between the two, but I perfer the ZuCable. The Cableplex Digital is only $20 and it is better in my HT than a $200 Tara Labs.

as far as cables, the Interconnects made the biggest difference, and the powercord on the DAC.

Yohjixme. I had the same problem when I hooked a Theta Pearl transport I got last week. Muddy, veiled and a fat midrange. Just like you, it turned out to be a poor mechanical connection. It all disappeared when I swapped digital cables around a couple times. And yes, Dekay gave me the same advice, which did the trick. Now I'm a very happy boy.

JK, I am definitely getting some low noise tubes.

Ton, I am not familiar with tubes at all, but you think the large plates is responsible for your increased soundstage? I did some research, supposedly those tubes your using were custom made and somewhat rare. Also, being on a tight budget, I've been dwelling on taking a chance on cableplex powercords or the ps audio minilab cables since they seem to offer tremendous performance for the money, $199 for 10 awg, 3x shielded (boy, i am starting to sound like one of those absolutepower ads).

The Tubes are available at www.upscaleaudio.com, I think they were around $20 each. They have a whole lot more if you want tho spend $$$. As far as increased soundstage, I think all of the upgrades, tubes and cables, made a contribution to the sound quality. I had the tubes recommended to me by Matt, the guy who makes the Cableplex cables. I am not familiar with the PS Audio, but for the money I think you will not regret anything from Cableplex. I have an Audiophile uncle who just upgraded his entire HT, and His daughters HT, to the cableplex Nirvana cables. This includes a special subwoofer cable.

As you can tell, I can't say enough about the cables, this is my personal opinion and the biggest enhancement to my system.

Good luck with your decisions