One tube pre-amp designer who does so for both the consumer and pro markets is Tim de Paravicini. His EAR-Yoshino pre-amps are designed to drive a 600 ohm load, the standard in recording studios. The EAR 868L has four pair of stereo outputs---2 pair unbalanced on RCA jacks, 2 pair balanced (via transformers) on XLRs.
