Marshall lists the 401 as a three channel 1 X 12 combo amp. It's actually a two channel amp with channel two offering settings for OD1, (gain), or OD2, (more gain). Four EL84s producing 40 watts and 4 ECC83s, (12AX7s), up front. One Celestion Gold Back 12" speaker in the open back cab. Channel one has controls for Gain, Treble, Mid and Bass. Channel two's controls are the same with the addition of a Volume control between the Gain and tone knobs. The 401s master control section features a mix knob for the parallel effects loop, a reverb control and a master volume.
This is a great little combo for someone who really wants the Marshall look and logo, but, prefers EL84 output tubes over Marshall's standard EL34s. I attribute the voice of this amp to a combination of the EL84s and the Celestion Gold Back speaker. These are the two components that provide the 401 with a sparkly yet darker rich tone all at the same time.
The Gold Back speaker runs to the dark side and would probably sound like a mushy crunch if it was used with an EL34 output section. The EL84s rebuild the focus and definition of the speaker's tone and help to achieve the distinctive voice of the 401. Think Marshall Blues Breaker X Vox AC30. Dark and toppy all at the same time. The 401 really sounds original and one-of-a-kind. I can't think of another amp that shares the 401s tonality. I've played through so many amps over the years that, just the fact that an amp sounds different from the normal market offerings, makes me enjoy playing through it.
The Marshall DSL 401 would be a hard amp to recommend for most Dino applications. It's far to mid-rich for metal and much to smooth for Led Zep. I guess I would place it in the range of tones associated with Queen's Brian May or, in a few instances, Pink Floyd's David Gilmour. Not so much Dino as it is progressive. I really don't think it should have been released as a DSL model. In a head-to-head comparison with the DSL 50, the 40 watt DSL 401 just sounds like it comes from a completely different amp line.
The Marshall DSL 401 has a known problem of overheating and melting a particular circuit board. The board and heat source are just too close to one another. The addition of a fan or upgrading certain components seems to be a common line of discussion on many Marshall web pages. When it's working, it sounds beautiful. If it fries itself during a performance the qualityof its beautiful tone might be lost among the chattter of the unhappy campers in the listening audience.
Mine's held in there. I've never needed support.
If you're a player looking for a mid rich uniquely voiced amplifier that carries the Marshall logo and has enough volume on tap to fill a bar or small club this would be an amp to consider. Keep it away from any backing wall and maybe use a fan to cool it down. I really love the tone of the Marshall DSL 401. I don't care for it's "overheating" issues.", and, would have never included it in the DSL line of Marshall amps.