There aren't many iPod docks with tubes around - and those that are seem to be quite 'spensivo. The iTPA-220 from Dice is a cheaper alternative for fifth-generation iPods, boasting a pair of perky Dual 6N3 tubes and 2x20-watt speakers.

iPod tube preamplifier
- True, audiophile quality music
- iPod charging
- Video output for use with Video iPods
- Remote control functions include: volume
control, mute, next/previous track, play/pause
- Dual 6N3 tubes for a warm analog sound
- iPod compatible docking station
- Auxiliary input for additional audio devices such as computers, non-Apple MP3 players and so on

Active Speakers
- Built in 2x20 Watt solid state amplifier
- 4" mid/bass driver and 1" dome tweeter for full dynamic range
- Solid constructed wood acoustic structure enhances the audio quality
- Bass reflex port for increased bass response
- 1/8" audio in.out connectors for preamplifier
- audio cables included

Costing $299, the iTPA-220 is shipping in September, but you can pre-order it on the Dice site now. [Dice Electronics via Playlist]