Distortion in System....Old Tubes???

[Spindrift]

Hi All:
I have the following setup (about 10 years old now).

* AMC CVT 1030 Tube Pre
* AMC CVT 2100 Tube Amp (80W)
* Pair of Linnfield 300Ls (by Boston Acoustics)
* Acoustic Alchemy Digital Decoding Engine v3.0 w/ Digital Transmission Interface v2.0

I'm recently getting distortion in the system at a slightly detectable level. This happens at any volume so I don't suspect the speakers. The tubes (Svetlanas) are about 6 years old now and they are the 2nd pair I've had in the units.

Could this distortion be caused by "used up" tubes?

On another note......When playing certain high volume-high output tracks, the woofers on my speakers move in and out slowly (even at medium to medium low volumes)...I don't think that it is low low end (5 Hz etc) and suspect DC. I have sent the amp in to be checked by AMC but they said all is within spec.

Any help/advice/suggestions are appreciated!
Thanks,
Spindrift

[E-Stat]

Could this distortion be caused by "used up" tubes?

The Svets (actually SED now) are good for around 3000 hours in typical tube amps. If you don't need new ones yet, you will likely soon. I'd buy replacements and see if the problem goes away. I recently retubed my amps. The outputs in my VTL 450s held bias, but after four years were in need of replacing.

Your motorboating could be caused by airborne feedback or simply because the outputs are worn out.

rw