A few months ago, I talked to Psychaudio who is a local amplifier designer, about building a device that will take an unbalanced signal, and create a balanced signal to feed to balanced amplifiers. This will make it easier for people who wants to have balanced drive on their headphones, but not owning a true balanced source.
Although a lot of people would object to this method, after the release of the Protector, we can definitely see that the improvements gained from having balanced drive is very noticeable even from if you have an unbalanced source.
Enter the Soul Drive, which utilizes a Burr Brown DRV134 chip to do the unbalanced to balanced conversion. As quoted from the DRV134 datasheet page:
The DRV134 and DRV135 are differential output amplifiers that convert a single-ended input to a balanced output pair. These balanced audio drivers consist of high performance op amps with on-chip precision resistors. They are fully specified for high performance audio applications and have excellent ac specifications, including low distortion (0.0005% at 1kHz) and high slew rate (15V/µs).
These are some pre-launch photos of the Soul Drive:
The capacitors are for the power supply, and there is no capacitors used in the signal path. Since the Soul Drive is an active device, it requires a 12V wallwart for operational.
I personally haven’t tested the Soul Drive, but a prototype unit is out and the early testers have been saying good things about it.
Stay in tune!