Hi beat,
I've been using an
IRD Purist for about a month and I'm impressed with it. For under $1K I don't know of a better built, designed and executed line level SS preamp. The Purist has bi-amp outputs, a superb swiss-made ladder stepped attenuator and adjustable gain. At '0' db gain you basically have a buffered passive line stage. Do check out the IRD circle here for more details.
The Purist is VERY quiet, transparent and believe me when I say that it exhibits NO typical SS hash, tizziness, peakiness or harshness. In fact, the Purist sounds smooth, coherent and musical with plenty of detail.

I also use a CR Developments tube preamp and a passive DACT attenuator. After spending quite some time comparing the Purist and the CR, I found that the CR adds a little more palpability and liveliness to the sound. Note that I used the word 'add' as in tube added 2nd and 3rd harmonics. This trait seems to compliment my Rowland 8T amp better than the Purist. But at the cost of a higher noise floor and susceptibility to hum. It is all about component/system synergy but I believe the Purist is just about as neutral as it gets.
I found out to my surprise that the Purist works best plugged straight into the wall without any AC filtering from my DeZorel Audio Reference Senior power filter. No other component I own can claim this. I asked Curt and sure enough, he has a good AC filter already built into the Purist. Hats off to you, Curt!
As you are bi-amping with both tube and SS (very different input impedances), an
active pre is a must. I found that the Purist drives my Mesa Baron tube amp very well.
Finally, I must point out that Curt is an absolute gem to deal with. He goes the extra mile
and the mile after that to ensure that his products are right for your system

. Highly recommended.