The Thermionic Solo Vulture is well regarded as one of the
best Valve Distortion units available on the market, is now on sale at Kazbar
for £850 or £1500 if you decide to buy two units to make a stereo setup – there
is very limited stock available, so get in touch if you’re interested.

https://kazbarsystemsinc.com/thermionic-culture-the-solo-vulture/

Here is a bit more information about the Solo Vulture;

Not be thought of as just ½ of a standard Culture Vulture,
the Solo Vulture has special extra features, including 2 switchable signal
paths controllable either by a toggle switch on the front panel or a foot
switch, which makes it suitable for stage use as well as in studios.

The Clean Channel goes straight from the 1st stage to the
output stage.

The Dirty Channel is amplified further after stage 1, and
then it hits the “distortion” valve, before the output valve.

Presence and Active Tuneable Mid Lift as found on the
Anniversary editions of the Culture Vulture can be added to the Dirty channel.

There is also a 4 position Low Pass Filter switch to remove
unwanted high top. The Presence adds 2 options of broad mid range to the sound.

The Mid Lift is most effective at low current settings (see
below) and can be used at all positions of the Distortion Type switch but is
most effective with P selected. It’s a high “Q” control with 4 active
settings tuned musically and, will really emphasise the guitar, bass or other
instrument in a mix or, of course, on stage.

The Distortion Type switch affects the way the distortion
valve is configured. “T” is Triode (smoothest 2nd harmonics).
“P” is Pentode (more aggressive 3rd harmonics), the most popular. SQ1
& SQ2 are the bizarre “squash” settings and should be used for
more extreme effects.

The Meter reads the actual current through the 6AS6 type
distortion valve. This is controlled by the Bias Control. When the valve
current is 0.25 – 0.3 mA its least distorted. Very low current gives it a
thinner more broken up sound. High current and it’s a bit fatter and
“woolly” 0.1 mA at SQ2 adds an extra octave to the sound (usually).

Inputs and Outputs are ¼”stereo jacks. The Line In on
the back is wired “semi floating” so as not to degrade the signal
from a DAW. The high impedance DI in on the front and the Line and low level
outputs on the back are unbalanced so the ring on the jack is grounded. Single
or 2 core leads can be used when connecting to balanced equipment