i dont' really see how tubes, a technology outdated by the invention of the transistor, will contribute to the pc audio industry. about the only thing it could really contribute is higher output with the same level of input (from the motherboard, about 5 volts)... this small increase in output volume is really not needed, since anyone serious about pc audio buys self-powered speakers. some will argue that tubes will generate a warmer sound, but this is generally achieved by tube pre-amps...not the output tubes. i'm also curious about the heat they would produce...
just my thoughts on the matter...