How to judge a preamp's sound

If the preamp looks really sharp it will sound fine.

@hilde45 FWIW even a cable and no preamp at all has a sound unless you jump through some hoops to prevent it doing so.


It helps to have recordings with which you are familiar. I use recordings I made myself (and have the master tapes) so I know how they are supposed to sound. But that is a luxury most people don't have, so start with recordings you've heard many times and then see how changing out a component seems to affect the sound of that recording. In a nutshell, that's how reviewers do it. This is entirely subjective so you won't get 100% consistent results. So a consensus of more ears is also helpful.

@atmasphere Thanks. Those are good suggestions. I imagine keeping the cables the same would be advised in any comparison.

I'm not presently involved in trying out preamps, but I still listen to reviews for fun. I thought I had spotted incorrect advice and was seeking to learn if that was true. 

The idea that a preamp should not have a sound is over simplifying its role.  
Ideally it should not add or subtract from the tonal spectrum and balance of the source but this is not realistic.  Preamps can be evaluated on their tonal presentation and balance and how well the do at the frequency extremes and how transparent and clean sounding it is.  
Also it should not add any additional noise or distortion but again this is not realistic. 
Finally the amplification withing the preamp can be evaluated on its representation of drive and dynamic energy.  For me a preamp should offer exceptional micro and macro dynamic energy.  
Bottom line- a preamp can easily be evaluated on its sound quality when compared against others.  Saying it should have no sound is a gross over simplification and not possible.  

If you’re trying to decide on a sports car, do you drive one car on a bunch of different roads to decide which one you like or would you compare several cars on the same roads? Sure, in the first case you’ll get a good idea of what that one car can do, but it’s not as helpful in providing a relative perspective and/or making a buying decision. And after all, isn’t that the most important information a review can provide to a reader? Reviewing one preamp with a bunch of amps is interesting and somewhat helpful, but IMHO it’s less effective than comparing one or more preamps to each other. Humans are inherently poor at judging things on an absolute basis and much better at judging relative performance. Every reviewer has had the experience of thinking they have the sound of a component nailed, then they substitute in a competitive product and they realize how off they actually were in their initial impressions. Without a comparison they’d have been way off in their assessment. This is why I always take reviews written without a comparison example with a HUGE grain of salt. Anyway, just my take on it.