Optical tubes – It's no oxymoron with DS Audio's new TB-100 [€17.5K], a dual-mono tube phono stage/equalizer for all their optical cartridges. Per channel a 12AU7 provides voltage gain, another output buffering. There are four selectable bass curves and a transformer-coupled input. Claimed bandwidth is 10Hz-70kHz, output voltage 500mV, output impedance 700Ω.
