He played this live once for Territorial Pissings on this show. https://www.youtube.com/watch?v=N49kYRC_EhQ

The cool thing about this power amp is it sounds good with more than just guitar, you can use it as a bass amp, piano amp and stereo system as well. But, no one really needs that much power unless you're playing to crowds of like 10,000 people.

In a photo from the "Psychedelic Sexfunk From Heaven" era, John Frusciante is seen using a Mesa/Boogie Strategy 400 Stereo Power Amp. The image, taken by Daisuke Hirata and shared on Flickr, provides insight into his gear setup.

The pictures in the source link confirm that Hetfield used this power amplifier at some point.

Used Live 1988-1989 during the Damaged Justice tour, he later moved on to the VHT 2150 around the recording of "The Black Album"

During the 1988 David Lee Roth and 1990 Whitesnake world tours, Vai used 2 of these power amps for two Marshall amplifiers.

As seen in Tracii's flight rack case.

In a user-uploaded photo on Photobucket, Dann Huff is shown using a Mesa/Boogie Strategy 400 Stereo Power Amp as part of his rig.

And what do you use live?

I have a Dual Rectifier and a VHT Pitbull. That’s in my rack, and when I’m travelling with my rack I do a left and right split on stage and in the PA, so it’s true stereo. A lot of guitar players never get that. I always tell them, first piece of advice, get two heads and a splitter. And I’ve even used a delay between the two in the past, and it really opens up the whole of the middle for the vocals and the kick and snare and bass. If you sit out front and listen to a true stereo guitar with two stereo heads, it’s huge. It’s way bigger than one mic. But a lot of the times when I’m on the road I’ll just use two Dual Rectifiers split, two full stacks. And it’s a lot of work to lug that stuff around, but either way, the Dual Rectifier, I would say, is my signature sound. I’ve been playing Boogies since our first recording on Epitaph, and that’s just the old school Dual Rectifier, one of the best amps I’ve ever heard in my life. It’s a very versatile amp, and durable. Y’know, it’s funny. I saved up and thought “I want to sound like Metallica,” so I went out and got a Mesa Boogie Studio 22 preamp and the Strategy 400 watt all tube stereo power amp, which was just insane. It cost me a lot of money. It cost $3500 bucks or something. I saved up all summer. And not to say that I’m that guy, but I’m pretty sure I turned the whole punk scene onto those Boogies. NOFX used it on their album, Bad Religion used it on their album, Down By Law used it on their album. After I recorded with it, Brett [Gurewitz, Bad Religion guitarist & Epitaph founder] was like, “Can I borrow it?” Then Eric Melvin from NOFX came down and he was really into it and he would up buying a Mark III. In the meantime I was trying to get sponsored by Boogie. I was like, “Hey look, you’ve got to hook up some punk bands.” And they were like, “Punk bands can’t afford our stuff. It’s too high end.” And I was like, “No, I’ve already got three bands that have bought it from you. Why don’t you give us some free stuff?” And they don’t give anybody free stuff. Maybe Metallica, I don’t know. But they’re one of those amp companies that really keeps it tight. And it’s hilarious because I look back on it and there was an article in a magazine entitled Boogie Man, and I just want to call them up and tell the old guy, “You know how many punk guys are using Rectifiers now? You owe me steak dinners for life!”

In the 1988 Headbanger’s Ball episode in which Anthrax hosted for the night (“It’s actually not late for us, It’s late for you”), Joey states Dan’s strategy “400 series” as a part of the gear he used at Montana studios.

"Bogner Triple Giant thru Mesa Boogie Strategy 400 (ABY Pedal) mixed with a Peavey 6505. I like to have the mids & highs of the Bogner at around 1 or 2 O'clock, and the Lows at 1 O'clock, exclusively thru the Sharp Gain channel. The 6505 was used to fill out the tone with more dirt and fatness."

In the video titled "Ian Antono Pindah Ke Lain Hati (God Bless Vlog #5)" on the God Bless Official YouTube channel, Ian Antono is shown using the Mesa/Boogie Strategy 400 Stereo Power Amp.

Sisters of Mercy gear list, circa 1991:

Tim Bricheno Squire Strat, 2x Squire Tele, Gibson 'Chet Atkins', 2xJC120, 2x4x12 Marshall cabs, 1x50w Marshall amp, Ibanez Tube Screamer, 2xBoss DD-3, Boss MZ-2

Andreas Bruhn

2xKramer Focus 1000 (with DiMarzio PAFs), Mesa Boogie Strategy 400, Mesa Boogie Quad pre-amp, 2xMarshall stero cabs, Quadraverb FX, Rat distortion, Morley wah-wah, Boss CS-3

Tony James

WAL Custom bass, WAL MIDI Custom bass, 2xAMPEG SVT amps, 2xAMPEG 8x10 cabs, Korg A3FX

Sequencing

Compac 386 portable PC, running Voyetra software, 2xAkai S1000, with external hard drives