These units are legendary and extremely hard to come by.

Serial #130, this one obviously shows some wear but works as it should.

I am not even sure if you can get these from Sunrise Pickup Systems anymore, but when you could, they were $5350.

Save a ton and get one of these units for a fraction of the original price.

If you own a Sunrise pickup or have ever wanted one of these units, now is your chance. I doubt you will find another one for sale.

Info from Sunrise:

S-TI

The Sunrise Tube Interface is an all vacuum tube, transformerless, high resolution line amplifier. The STI reveals nuance, detail and openness with a quality usually reservered for only the finest studio microphones. Reproducing the natural voice of an acoustic guitar in the studio with only a microphone has been surpassed by the Sunrise Pickup and STI, which has become the highest standard of the industry for both live performances and recording.

The Sunrise Tube Interface delivers +20 dB of gain, and has two unbalanced outputs (XLR and 1/4″) with headroom in excess of +30dBv. This Tube Preamp with its unique ability to access the Sunrise Pickup’s coupling design will deliver the sonic quality and resonance of the instrument being amplified. Frequency response is flat from 2Hz to 50kHz + or – 1 dB. The two 1/4″ input jacks are in parallel with an input impedance greater than 2.0 megohm to insure against pickup loading. A true 600 ohm output impedance will drive extremely long cable runs without signal degradation.

Specifications:

Gain: 20dB + or – .3dB

Input Impedance: 2.2 megohms

Output Impedance: 680 ohms

Frequency Response: 10Hz to 100kHz + or – .5dB 20Hz to 20kHz + or – .1dB

Distortion @ +4 dBm: 20 Hz @ less than .006% THD

Distortion @ +4 dBm: 1kHz @ less than .003% THD

Distortion @ +4 dBm: 20kHz @ less than .006% THD

Noise: less than -84dBm unweighted

Maximum Output into 10k ohms or greater: +32dBm @ less than .01 THD

Maximum Output into 600 ohms: +20dBm

Power Requirements: 110 to 120 VAC 50-60 Hz Less than 32VA