The 333XL/333XL-212 is the big brother to the 333 Series, with four key additions: Overall active Presence control. Comes loaded with EL34 power tubes for a more compressed, tighter midrange. Noise Gate on Lead channel. This is an ANALOGUE gate that will never close or shut you off in a clean passage. It is designed to decrease high frequency noise and hiss without changing your tone and it works loads better than a lot of competitors' gates. XL switch on Crunch and Lead channels. The XL function will add more "chunk" to your sound. You can add some thunder to the combo version to more closely emulate a 412 cab, thicken the sound of single coil pickups or add sustain to single-note melodic passages. After that, this design is much like the 333 with three fully independent channels: A totally Clean channel that won't break up; a Crunch channel for a "halfway dirty" rock and blues tone (or crank the gain for a metal rhythm tone); and a Lead channel with the same structure as the Crunch channel, but with access to more gain. Each of these channels has its own volume feeding the overall master volume, giving you total control over the level of each. Infinium Valve Life Multiplier Technology. Our revolutionary Infinium Valve Life Multiplier technology is like having your very own technician inside your amp constantly monitoring and tweaking valve performance for the ultimate in tonal integrity and reliability. This revolutionary circuit not only optimizes the performance of each output tube, it dynamically balances the drive between them to more evenly distribute the load. With Infinium, your tubes last up to 20 times longer, saving you substantial money over the lifespan of your amplifier. Infinium also compensates for the effects of aging, automatically adjusting current levels to keep your valves sounding as good as the day they were installed.