Best budget preamp for my entry level system?

How about a used Proton integrated amp? They have pre/amp in/out jacks, so can be used as a preamp. I have one that I paid $50 for! Made in Taiwan at the same factory as NAD, back in the 80's. These are killer-sounding integrateds! Both pre and power sections rival today's four-figure gear! If I had nothing else I could happily live with my Proton!

A receiver with pre-amp outputs might be a good option! I have a NAD receiver with pre-amp outputs stashed in my storage, but was leaning towards not using that particular piece because I find it to be bright, and might not be the best pairing with the Zu / Emotiva equipment.

The terms budget system and pre-amp do not compute. Being on a budget it was quite frankly a mistake buying a separate amp. Separate pre-amp and amp greatly increases the cost and complexity of your system. Integrateds are by far a better value especially when trying to save money. So much better in fact you will be well advised to sell that Emotiva amp and Marantz receiver and then with the funds buy the best integrated you can find.

(You might want to keep the Marantz. It has a tuner and a phono stage you can use, and it just plain looks good. The Emotiva though just needs to go.)

As for integrateds there are lots to choose from. A few things to consider- tube or solid state? Find a few to compare by listening. Do not go by watts or any other specs. That is how you wind up with boat anchor monoblock power amps. You want a budget system you need to be selecting by listening comparisons.

You play records. Good. The phono stage in your Marantz is your baseline. Its a pretty low baseline. Just about anything you get will be a big improvement. There are some integrateds with built-in phono stage, and there are lots of budget stand alone phono stages.

As far as stand-alone phono stages go, keep in mind the situation is the same as with your preamp power amp in that they need to be connected. That means another interconnect, and another power cord. You don't have to spend a lot on those but you won't get as good sound if you don't either. So at the budget end you'll get the most sonic bang for your buck with a good integrated with a decent phono stage.

What is good? What is decent? Only way to know, listen to em.

Check out the Schiit Audio Saga.  They are clearing out the last of them with intro of the upgraded models.  It's on B stock for 200.  I bought this and compared it to my Parasound Halo P5 and it was no contest.  The Saga was clearly superior with more detail and therefore imaging.  

Buy their stand alone phone pre and you're set.