The $10,000/pair 234 Mono from Woo Audio sets a new standard for extravagance — and, perhaps, sound quality — among headphone amps. The 234 Mono uses a separate single-ended triode tube amp for each channel. An adapter combines the outputs of the two monoblocks to fit a standard headphone plug. Stepped volume controls make it easy to balance the two channels. You can even use the humongous output tubes of your choice: one 2A3, 300B or 45 per channel. Plug-in “keys” reconfigure the amps for each type of tube, and another key lets you use the amps to drive speakers instead of headphones.
