You believe preamps all have their own sound flavor and that you must spend 1k plus to get decent sound, but then recommend without reservation using the analog out from a pc that may be using onboard sound or who knows what as dac and analog section??
Methinks your head is filled with much audiophile voodoo and little practical knowledge of modern devices.
To the op, if you want to use the computer as a source to play stored media, please use a digital connection into the preamp or receiver. Depending on what source you are talking about and what playback options you want, this could be coax, optical, hdmi, or even usb to an inexpensive outboard usb dac (good quality units can be found for $50).
As for preamp suggestions, if you only want two channel and must have an audiophile pedigree name with lots of praise in some audiophile publication, and are willing to sacrifice any modern processing, codecs, digital inputs, etc, look for a used older rotel analog only prepro or similar from other brands.
If you think you'll find features such as modern based management, video switching, codec decoding, etc useful at some point the look for a budget avr which is designed to do these things. If you want to use your current power amp, make sure it has preamp outputs and then do so.