Having marshall amp on album cover?

You mean I shouldn't wear anything on album cover since it's branded?
Gosh!!!!!!!! :confused:
Once you are past a certain level of prominence, you don't want to. First of all, if you are someone with a large following, your endorsement is worth money. Why advertise other people's products for free, whe you should be getting paid for it. Second, if you have money, or are percieved to have money, you run the risk of these companies deciding that your image doesn't fit with thier image and try to sue you for damages.

If you are just a local act that will be selling a couple hundred CDs at shows in you area, it doesn't matter at all.
I wear Mexx. One day they'll come and tell me "You don't fit our clothes. Take it off! Never take pictures for album cover with those t-shirts on!"
I play Roland digital piano. One day they'll come and tell me "Your playing skills and your songs suck! Don't ever play our keyboards."
I buy them my money anyway. I think I have some rights to use them for any purpose as long as I don't smear their brands.
A bit late, but better late than never. I don't know if the OP already decided what to do (nope, I didn't read all the 13 pages) but here it goes my experience for whose is interested in the matter.

I have no idea how is the copyright stuff around the world but here in Brasil it may be a pain in the ass. I wouldn't make an album cover (or any other commercial artwork) using anything that I wouldn't be allowed to. The reason is because I already was enrolled in a process because a similar thing and it was not fun. Long story short it was a book cover that I was hired to make the artwork with a picture given to me by the client. Happens that she didn't have the rights to use the photo and the widow of the photographer processed her and she found a way to drag me together in a coward attempt of slip off while I was eaten by the wolves. Although I could prove that the client was the real culprit and got inocented at the end I still had a lot of stress and headache, wasted a lot of time in several comes and goes to the court and no one gave me back the money I spent with the lawyer, travelling (it was in another town), etc.

It turned me a bit freak about copyright stuff. Actually I think that copyright is the kind of thing that shouldn't exist. I trully believe that EVERYTHING regarding to culture should be free and humanity patrimon. But there is a huge distance between what I think and how things are. So now I never use something without permission, specially if the owner of the copyrighted thing is from the same country as I live, because if they decide to process you there is no way out. Things may be a bit more cloudy if you are at a different country because copyright laws don't reach people overseas. Well, theoretically they do, but in the real life it's too much more complicated.

A few things to keep in mind in the OP case. First, I think that it depends how the image of the Marshall amp will appear in the album cover. If it is a band picture with the amp somewhat appearing just because it was there in the stage, I think that it may not be a problem. But if the cover is based on the amp, like a front shot it is different. Also, if you are a big kick-ass band that is going to sell millions of copies, maybe they (Marshall) can get upset because you use their product picture and decide to bite some of your profits. Or they may simple love you because you are making a free advertisement as if you were endorsing their equipment. In the case of a small band that will sell a few dozen of CD copies, I doubt that the company would care about to make their juridic department to scratch the butt. Nonetheless it is not a rule. Certain companies like Gibson, for instances, will stalk anyone that they think that may be eating their breadcrumbs. I know of a luthier guy that was building a very limited number of half-scale Les Paul guitars and was told by Gibson lawyers by letters to stop doing that or they would take the 'necessary actions'.

Good luck!

So its been a few years.... did Marshall ever get back to you?
I have the same question in regards to an album cover that has my Marshall stack prominently in the image (you can see about half the "Marshall" lettering, due to some of the amp being blocked by another item).

If you are really worried about it, edit the image to block out the logo. In the past, in music videos, it would be standard operating procedure to put black gaff tape over logos on amps. Now that can be done digitally, after the fact.

Like I said before, you don't need to be advertising for Marshall.
Don't forget that the reality is it's all down to money. If an amp is featured in a movie that means sales figures suddenly peak - the manufacturer is likely to be very happy with product placement. If the movie is about an axe murdering guitar fiend then the madman playing through a Marshall might well be banned. Like the alleged iPhone promotion of iPhone usage by the goodies and the blanket ban on iPhones being used by baddies. The BBC have a nice big sticker across the branding on the morning TV presenters laptops. The BBC used to be amazingly crazy about their no advertising stance - years back black tape covered up the brands on Children's TV - they'd make something using a very obvious soap powder box with the brand blobbed out. Fablon - was routinely replaced by the term 'sticky backed plastic.
I would imagine that it depends how prominently it's displayed. If it's advertising Marshall, it would be copyright infringement. If there's a band in front of it, or other instruments, it would probably be fine. In the same instance, how many guitarists have Gibson, or Fender in their hands.

I think in the long run, why would an amp maker care? Even if you were blowing it up or setting it on fire, it's free advertising.

On an unrelated but amp note: It took me years to get Jimmy Page's ORANGE stack joke. OR GE.