Looking for opinions on low noise preamp design - is my reasoning correct?

[PRR]

> JFET, common source  ... 10K drain resistor....I am not convinced that the output Z is in the 1K area necessary. Can someone help out in this area?

http://www.guitarscience.net/theory.htm
http://www.guitarscience.net/papers/jfet.pdf

[tempus]

Thanks to everyone who has replied to this post and tried to help me out with this design.

I've done some more research and testing and have designed a TL072 based circuit that will give me 21nV/rtHz noise, which should be adequate for my needs. I did some tests and found that the noise floor of my interface is -90dB, and that connecting this preamp to it adds no new noise (at least not according to the spectrum analyzer or my ears). R.G. kind of hinted at this in his post - there is a limit to how much you can improve upon what you have; in trying to design the lowest possible noise circuit, I discovered that the lower noise probably won't make much difference since it's actually lower than the interface noise contribution. Also, finding out that it's not necessary to match the input and feedback resistors was a huge help, since this drastically reduced the noise contribution from resistors, so thanks to those who pointed that out to me.

I did experiment with some discreet designs, but I found that they added a considerable amount of power supply noise in the form of hum compared to the TL072. This is something that I hadn't even considered, and it appears that the TL072 has superior PSRR qualities compared to the JFET designs.

I also came across this great video: https://www.youtube.com/watch?v=W0vfALQ_n54 which nicely explains how to calculate circuit noise.

Thanks again for everyone's help; this forum is a great community of people who so generously share their time and knowledge.