How much difference does a phono preamp really make?

@artemus_5  I can hear a difference between the two carts. Not so much with the two phono pre's

@earlflynn  I'm very sorry to hear about your stepson. Thank for your input. 

@dekay  I did. The Denon sounded better on the MC setting although I believe the manufacturer recommends using MM. 

Thank you to everyone else so far. It seems like my carts may not be good enough for me to notice a difference between my entry phono stages. 

I posted a question to the Technics SL1200 group on Facebook about recommended cartridges. Most seemed to point to the ATVM760 SLC. Would this be a significant upgrade to my Denon and Clearaudio?

Thanks!! 

It can make a huge difference.

First fundamental step is make sure phono input specs match cart output specs ie the two are compatible. Then you are baselined optimally to assess any other differences from device to device, if it still matters enough to you.

Of course its a system so everything else downstream from pre-amp to speakers to setup in the room matters as well. The trick is to figure out the weak link and focus on that as needed. Don’t get too hung up in one place.

If that sounds hard, then consider one the many integrated solutions available today and there are many very good ones capable of competing with many high quality separates. The engineers ie the technical experts have integrated the things that matter for you there. That can help take a lot of the guessing out of the game. You still need to pick a cartridge that is compatible and in many but not all cases speakers as well.

@ audionoobie OP

I can hear a difference between the two carts. Not so much with the two phono pre's
It seems like my carts may not be good enough for me to notice a difference between my entry phono stages.

OK, that changes the answer for me. Both preamps are about equal sonically so you won't hear a difference in them. But the carts are doing their job. You can hear a difference.  Though your carts are not really high end, they will respond much better with a better phono preamp. Remember the hierarchy I posted. The cartridge was the least important. 
Atmasphere noted as much telling how a lesser cartridge sounded great on a better arm & TT. The phono pre will also give better and is where I'd spend my $$$ now. 

I have experienced many phono stages, and in general they are extremely important in the system as a whole. They are far up the signal path and dealing with a minuet signal, they must be very quiet and high quality to do it well. However, also the basic rule of thumb applies to Phonostage… “you need to double the cost of a component to get a solid very noticeable improvement” (its just a rule of thumb… but typically after you get into components over a couple grand it works pretty well).

For me, there was a rather massive improvement in going from a Schiit Mani to a Rega Aria Mk3.