Pyle makes plenty of stereo preamps with gain controls, but I would consider Pyle PA-grade stuff. Most of their stuff lives up to their name, Pyle-o-crap.
The problem with 2-channel is that there really isn't anything decent under $600. Marantz makes some decent 2-channel stuff but it is all above $450.
Maybe tell us what you have looked at or are considering and see if anyone can comment further.
Denon AVR X7200WA, Emotiva XPR-5, Emotiva XPA-7, Sony XBR 75" 850C, Oppo BDP-103D, Roku 4.
DefTech BP7000SC (L/R), CLR3000 (C), SM55 (FH), UIW BPZ/A (SB), UIW 75 (TM).
JBL L7 (Sur), EoSone RSR 350 (RH).
PC 2.1 setup. Emotiva Stealth 6, SVS SB2000 sub, Emotiva DC-1 DAC.