I agree wholeheartedly with Millercarbon, It would make your system much more complicated. Yes It's a good idea if you want to seriously upgrade your system , but your next step given your budget is to my mind to consolidate sell and start over and and buy integrated.
You read what these audio nut bags, myself included ,spend on just a piece of wire. I am pretty cheap by these standards. I was already to tell you that the best pre to get is a 6SN7 based unit but these run about $1,200 which is cheapish for high end pres but way out of your budget.
You've done it and started the slippery slope,by buying an amp, well if I were you I would patiently scour the used market for a great deal. But There are a lot of headphone amps that are also pres and the Schiit suggestion seams cogent if it has a phono stage you might want to give it a go.
You read what these audio nut bags, myself included ,spend on just a piece of wire. I am pretty cheap by these standards. I was already to tell you that the best pre to get is a 6SN7 based unit but these run about $1,200 which is cheapish for high end pres but way out of your budget.
You've done it and started the slippery slope,by buying an amp, well if I were you I would patiently scour the used market for a great deal. But There are a lot of headphone amps that are also pres and the Schiit suggestion seams cogent if it has a phono stage you might want to give it a go.