LA45 I found the Siemans they sent with the preamp to be wonderful, and in fact the stock EH tubes are quite good too. The unit is just so awesome that I wanted to try the NOS tubes suggested just to see if even more performance is possible. I will be trying my NOS and will report the comparision in about a week. Sherod and others may already be able to answer your question in more detail but the preamp definitely sounds great without the NOS treasure hunt. If I played it even with the stock EH it was a dramatic improvement over any other preamp I had heard.
