David Gilmour used a Fender 'Silverface' Dual Showman Reverb amplifier during the recording sessions for "Wish You Were Here," as confirmed by Kit Rae in "David Gilmour Tone Building."

John Dwyer is known to use a Fender Silverface-era Dual Showman Reverb head, as detailed in PMT Online's gear guide for Thee Oh Sees' new album by Richard Bloomer.

Berry used two stock Dual Showmans (Showmen?) live, as stated in this November 17, 2008 Premier Guitar article, this concert rider taken from this The Smoking Gun page and this December 15, 2011 Questia article. Listings for two of Berry's 1971 D.S.R.'s are linked here and here.

Premier Guitar, "My Amps' Date With Chuck Berry"

He confided that Chuck preferred to play through two Dual Showman Reverb amps, unaltered from factory specifications. “Hmmm,” I thought, rubbing my hands together like a little fly about to feast on a tasty morsel. I then asked, "What would be a fair rental price for you?” He said, “Well I could pay $300 if that sounds fair.”

Not wanting to appear too eager I said I thought that should suffice and made arrangements for someone to come pick up the amps. Only having a Lincoln Town car, I knew I couldn't load those behemoths by myself. So it was agreed that Sharna would come by in the early afternoon of the concert to help fetch the amps. I later found out that Mr. Berry has a stipulation in his contract that unless two Fender Showmans are provided by the promoter, there is an additional $5,000 fee for his performance. This made me feel like my $300 was a paltry fee in light of this information.

Questia

Since his '70s comeback, Berry has managed his own career, and his concert rider has included the following provisions: "Three professional AF to M muscicians, capable and familiar with Chuck Berry's music, to serve as a backup group which must consist of only a 'show' drummer with drums, a pianist and a grand piano, an electric bass guitarist with a bass guitar, and two unaltered Fender Dual Showman Reverb amplifier sets." Now that's rock and roll.

Vintage and Rare listing

I would like to offer my Fender Dual Showman Reverb amp with the original cabinet (2x15'' JBL) and flightcase that comes with it. I bought the amp for rider.nl, which is a backline company in The Netherlands. The amp was used by CHUCK BERRY on an European tour in 2007-2008.

The amp is in superb condition and had a retube this year.

2017 Reverb.com listing

UNIQUE FENDER DUAL SHOWMAN REVERB (HEAD+CAB) FOR SALE PROFESSIONAL FLIGHTCASE FOR THE 2X15INCH CABS.

CERTIFICATE OF AUTHENTICITY INCLUDED.

YOU CAN SEE CHUCK BERRY USING HIM IN THE LINK BELOW: [Chuck Berry, Let it rock Amsterdam 19 nov 2008]

In an interview with Vintage Guitar Magazine, John Fogerty mentioned that after Creedence Clearwater Revival broke up, he replaced his old and beaten Kustom Amps with more reliable Fender Silver Face Dual Showman Reverbs and Marshall JMP 2203 Heads for live performances. For studio work, he switched to Marshall 2104 Combos and Modded Silverface Fender Twin Reverbs for more gain.

Albert King playing Blues Power Fillmore East Live 1970

According to the inner sleeve of Rick Wakeman's album The Six Wives of Henry VIII, Wakeman ran all his sounds through a Gender Showman amplifier on the album. This detail is supported by an image available on Equipboard.

This photo from 1970 shows Peter playing his Fender Bass VI Electric Bass Guitar through a Fender Dual Showman Reverb Amp Head.

Brian Bell posted an image of his studio setup where a Fender 'Silverface' Dual Showman Reverb amp is visibly present at the top.

Used in the "mid-70s", as stated in this July 13, 2017 Music Radar interview.

His mid-70s bass setup was modelled after that of a local hero, Allman Brothers Band bassist Berry Oakley. “I had two Fender Dual Showman reverb amps: one cabinet with two 12s and one cabinet with four tens,” he remembers. Although Mills is most often associated with the Rickenbacker 4001, he went through a series of basses before finding the Rick.

“I played a beat-up Hofner for a while,” he says. “Then I played an Ampeg Dan Armstrong clear acrylic bass, followed by a Fender Musicmaster, and then I found that ’71 Rick.”

The 4001 remained Mills’ instrument of choice “until one of the horseshoe pickups went out. We couldn’t find another one.” He got a factory-replacement pickup, but wasn’t happy with it, so he went through another series of basses - an Ibanez and Guild among them - before trying out a 1970 Fender Precision he calls Old Yeller after its original finish.

“I had sort of resisted the P-Bass,” he says, “because everybody played them. But then I found out why. It was because they’re the best, especially for live shows. They’re just so durable, and they don’t go out of tune. They sound fantastic, and they feel good to play.”

Eventually, though, Mills’ bass tech located a working vintage horseshoe pickup, and the 4001 was returned to active duty. It’s actually a 4001S with Rick-O-Sound stereo output. “But I’ve never used it,” laughs Mills. “We tried it, but it was more trouble than the sound was worth.”

Mills has made a point of avoiding bass guitars with more than four strings. “I can’t stand them,” he says, admitting that five-string basses “just confuse me.”

In this Levitation session, at 0:39 you get a good look at the dual showman’s extra knobs behind Jean F., and at 3:55, you get a good look at the reverb out wires common on these models.

In a photograph accompanying an article by Peter Keepnews in The New York Times titled "Sam Andrew, Guitarist for Big Brother and the Holding Company, Dies at 73," Sam Andrew is seen playing a 1964 Gibson SG Standard through a JMI Tone Bender MK I into a Fender Dual Showman Reverb TFL5000D Head on a 2x15 Fender Cabinet (circa 1968-69).

You can clearly see this amp behind Tom