I have a set of professionally balanced Hafler amps. I need a good preamp for the system

Try a Schiit Freya +...an amazingly well designed preamp.

Thanks. I’ll check it out.

Check and audition a warm preamp with those amps. Just an opinion. 

  A preamp which has a lower tone.

 If u want used, I would recommend the Onkyo p-308,
amazing preamp, great tone, fun.

I find the Haflers to be on the warm side. Have they had any modifications ? If you buy the Freya ( the + would be my recommendation ), you will need a phono preamp. You might want to consider going passive ( I have ). The Freya gives you that option. Enjoy ! MrD.