Soldano X99 + SLS 105 — Ultra-Rare Matching Rack System

Soldano/Caswell X99 MIDI Motorised All-Tube Preamp (Serial No. 290) + Soldano Super Lead Slave 105 Tube Power Amp

For sale: an exceptionally rare, complete Soldano tube rack system — the Soldano/Caswell X99 MIDI motorised tube preamp, serial number 290, paired with the even rarer Soldano Super Lead Slave 105 (SLS 105) all-tube stereo power amp. This is not merely a preamp-and-power-amp combination; it is a cohesive, American-built Soldano rig designed around the same high-performance philosophy that made the SLO-100 legendary. With only around 300 X99 units produced and approximately 50 SLS 105 power amps made worldwide, a matching pair is a genuinely exceptional find.

A Complete Soldano Tube System

The X99 is a true all-tube 1U preamp using 12AX7 tubes, with Clean, Rhythm and Lead channels and the famous Soldano mid-forward gain structure. It offers real analogue tone shaping combined with MIDI-programmable motorised potentiometers: recall a preset and the physical knobs move to their stored positions.

The SLS 105 is the perfect partner. It is a 3U stereo tube power amplifier delivering 50 watts per side, using two 5881/6L6 output tubes per channel, with 4, 8 and 16 ohm speaker outputs on each side. Together, the X99 and SLS 105 form a compact but extremely powerful all-tube guitar system with authentic Soldano response, dynamics and harmonic richness.

Exceptional Rarity

The SLS 105 is believed to have been produced in very small numbers — approximately 50 units worldwide — making it substantially rarer than most boutique power amps. The X99 is itself a discontinued, highly collectible preamp, and serial number 290 places this example firmly within its limited production run.

Finding both units together is especially unusual. This is an opportunity for a collector to acquire a rare, matching Soldano rack system — and for a player to own a fully usable, professional-grade tube rig with genuine vintage boutique character.

The Soldano Sound

The X99 delivers the classic Soldano voice: thick low end, assertive mids and a smooth but cutting top end. Its Clean channel is open and musical, the Rhythm channel provides fat, responsive crunch, and the Lead channel delivers the tight, flying, harmonically rich high-gain tone for which Soldano is renowned.

The SLS 105 adds the crucial power-amp dimension: a punchy, dynamic 50/50 stereo tube output section that gives the preamp’s tones weight, authority and three-dimensional depth. Its all-tube power section responds naturally to picking dynamics, making soft passages breathe and heavy riffs hit with real force.

Stereo Power and Professional Flexibility

With two independent 50-watt channels, the SLS 105 is ideal for stereo effects, wet/dry rigs, dual cabinets or a large mono setup. The X99’s MIDI control and motorised controls make it easy to switch between radically different sounds during a live set, while retaining the tactile feel and analogue signal path of a genuine tube preamp.

This system is equally at home in the studio and on stage. It is especially compelling for classic rock, hard rock, metal, progressive rock, punk and modern heavier genres, where clarity, note separation and powerful dynamics matter most.

A Rare Opportunity

A standalone X99 is already a desirable collector’s piece. A matching X99 and SLS 105 — serial-numbered preamp plus one of only around 50 SLS 105 power amps ever made — is a rare chance to own a complete, historically significant Soldano tube rack system.

This setup is only sold together and ready to play for years to come

Mains voltage is 220V for both.

Contact me for exact shipping prices.

The setup will be shipped seperately, securely and insured.