Both are single channel tube preamplifiers...The UA Solo/610 is a simplified version of the M610. The old 610 boards were used on some great classic recordings, so the sound is well known. What if any are the Sebatron preamps based on? Both are similarly priced. Sebatron: - uses a single 12AT7 - Mic input 300ohms - Max gain 60dB Solo/610: - uses 1 12ax7 and 1 6072 - Selectable 500 ohms or 2k ohms (Microphone) - Selectable 2.2M ohms or 47k ohms (Hi-Z Input) - Max gain 61 dB - Freq response 20 Hz to 20 kHz +/- 1 dB Clearly different in build. Would you say that the Sebatron is more transparent of a design than the 610?