Question about Spectral DMA-180 Power tube

Can anybody tell me where I can by Power tube for Spectral DMA-180(mkII)?
I bought a few years ago from a bro, recently the power tube worked down... and it was over warranty.
I plan to buy new pairs, but don't know where to buy.

Appreciate whoever told me.
TKs again~~
I thought the Spectral amplifiers are all solid state, no tubes. Is there a different name for what you're referring to as a "power tube"?
Yes something's definitely amiss here...
yep no tubes in any Spectral gear I am aware of and certainly NOT in the DMA-180 in question ... I suppose you COULD drop any tube that would fit inside the chassis though :)
radio shack. i think you mean the light bulb that backlights the spectral logo when you power on the unit? if so, radio shack should have a replacement.