The Ultra Lead uses KT88 power tubes which blow away 6L6 and EL84's for power, clarity and tight bottom end. They also produce alot more real power. There are also different textures and gain stacking capabilities.
I currently have several VHT amps including the ones that you mentioned. And since I'm a big rack guy, I am using VHT Valvulator GP3 preamps and the 292 power amps. They are identical to the Pittbull Ultralead with Midi control added.
Ultralead and CLX:
The Ultra-Lead & Hundred/CLX designs share the legacy of the first true 3-channel tube amplifier on the market. These 100-plus watt amplifiers are state of the art, offering an array of features and simplicity of operation unique in all of ampdom.
The flagships of the Pittbull® line, the Ultra-Lead & CLX now feature Gain-Stacking™ in the Lead and Rhythm channels. Preset your channel gains for subtle, biting clean, robust, chunky rhythm, or searing, pummeling overdrive, then let the footswitch do the rest.
The cleanest, quietest effects loop in the world just got better with the addition of a switchable parallel mode. Mix the true amp sound with your favorite effect or process the entire pre-amp signal. The choice is yours.
Guitar Player Magazine described the Pittbull the best: "The VHT Pittbulls... deliver all the features you expect from a modern rock amp. Super high gain, an intelligent effects loop, bullet-proof construction and super clean tones --- something the others seem happy to ignore."
The Ultra-Lead's KT88 power section provides ample clarity and definition in the clean mode as well as in the full-on high gain channels. If more low mid-range punch is your game, just switch the power tubes and experience maximum 6L6 expression.
Guitar World Magazine wrote: "...the well-built, cleanly designed Ultra-Lead is aimed directly at no-excuses professional players... Whether you're after versatility, great tone, or sheer volume, the VHT Pittbull® clearly comes with an equally impressive measure of bark and bite."
For those who prefer more power amp distortion and less preamp gain, the Hundred/CLX is the ultimate EL34-based amplifier delivering in excess of 100 watts RMS of smooth, dynamic Class A/B power into 4, 8 or 16 ohms.
For smaller venues, the Dual-Class™ mode offers the choice of Class A, Class A/B or both. Unlike the combination Class A/B-Triode mode employed by others, Dual-Class™ gives you true cathode bias operation on demand. Fat'n honkin in the Half Power mode, or chunky 'n sweet when combined with Class A/B at full power.
Prefer 6L6 chunk to EL34 bite? You'll get more than just a bias change when you switch to 6L6 Pittbull® power. No other production amp gives you both screen current and bias voltage compensation when switching power tubes.
And this is the CL:
There's really nothing like sound of a cranked 50-watt amp. The perfect balance of power amp clip and transformer saturation makes your fingers come alive.
With the Fifty/CL, we've combined two of our most popular preamp voicings with an EL34 50-watt power package that's already becomming our latest runaway best seller.
Offering Gain-Stacking™, foot switchable boost and Series/Parallel effect loop, you'll think this is the most feature-packed 50 on the planet. But just to make sure, we've added our new Class A mode switch, Tube Rectifier and 6L6/EL34 switch. And there's more -- an optional, 3 spring Accutronics tube-driven reverb and a six band assignable graphic E.Q.
Once you fire up the Fifty/CL, you'll know you've heard the last word in 50-watt glory.
We haven't forgotten about you diehard 100-watt fanatics. Our Hundred/CL has all of the features of the Fifty/CL with power mode and optional twin Tube Rectifiers give maximum dimension to the 100-watt class.
Whether you prefer 6L6 punch or EL34 cruch, the Hundred/CL gives you features, style and unbeatable performance.