Preamp match for my First Watt F-7 amp.

I have an F5 and a J2. So I’m in the low gain club also.  I run an Aric Audio Motherlode II in my main system,and his Unlimited gets in the rotation downstairs. His preamps have adjustable gain,which really works out great with low gain amps,and high gain amps.  The Supratek that’s been mentioned earlier will also suit your needs.  

Don sachs with adjustable gain. What a guy!

Don only makes one model now with a fixed gain of 18db

I feed a FirstWatt F8 from a Van Alstine Transcendence RB 10 preamp. I rarely have the volume control past 10 o'clock. The sound out of Focal Aria 906's, rated 89.5 dB sensitivity, is terrific.

I am on a preamp testing binge right now so my first question to you would be what kind of sound are you going for? My second question would be how handy are you and do you think you would want to build your own preamp? There is an active DIY community building various Nelson Pass/First Watt designs over at diyaudio.com. I have built Waynes Burning Amp 2018 Linestage (BA2018) as well as the Korg Nutube B1. The BA2018 has a very transparent, detailed, clear solid state kind of sound. Building it would require more effort since it doesn’t come as a kit. But the Korg Nutube B1 is available as a complete kit for $299 at diyaudiostore.com. As built the Korg B1 is quite good but if you follow the advice of various posters on the thread devoted to that build by upgrading to top notch film capacitors and beefing up the power capacitors you can have a truly excellent preamp for less than $500. The Korg is more of a tubey, warm, holographic soundstage kind of preamp. It is a very easy build and the results are excellent. Both the BA2018 and the Korg Nutube B1 provide about 16 dB of gain.

Of course if you are looking for a more flexible preamp that supports multiple inputs with balanced as well as XLR ins and outs and a remote you would be hard pressed to do better than the Schiit Freya +. Sound quality is good but not quite top notch and it is right around your $1000 price point. It offers 12 dB of gain in tube mode.