tube pre amp plus solid state power amps?

Suikang, The output impedance of the Cary SLP-05 preamp is only 400 ohms not 400K or 400,000 ohms. The input impedance of the Rogue M150 is indeed 200K ohms or 200,000 ohms, which is 500 times the ouput impedance of the SLP-05. Many say the ratio should be at least 10 and I like to see a ratio of at least 20 for input impedance to output impedance to avoid rolling off the low frequencies. The input impedance of your Rogue amps is about as high as it gets (a good thing) and the resulting ratio of 500 will work just fine.

I have owned both of those amps. The McCormack is good but may not provide enough of the type of sound you are used to. Also, be very careful when matching tube preamps with SS amps. The McCormack has an input impedance of only 10K ohms and you want to have at least a factor of 10 (preferrably 20 or more) between the output impedance of your preamp and the input impedance of your amp (amp input imp. being 10x or more greater). Be careful of the preamp manufacturer's specs since some list the output impedance taken at 1K Hz while the actual high output impedance may be much greater in the bass due to limited coupling capacitor size. In the case of the McCormack, this would prematurely roll off the bass. Try to find information such as JA's Stereophile "measurements" on your preamp. The Clayton's generally have a much higher input impedance (my M200's are 100K ohms) and would mate well with virtually any preamp. The Clayton's are very nice SS amps and would provide much closer to the sound you are used to with your tube amps than the McCormack. Also consider hybrid amps such as Lamm M1.2, Blue Circle or Moscode. These use tubes in the earlier stages and SS ouput stages. The Lamm's in particular are excellent. I have not heard the others.

I made a recent switch from Lamm M1.1 hybrid (100wpc pure Class A into 8 or 4 ohms - unlike M2.1 or 2.2 which switch to AB at certain power levels) amps to Clayton M200 SS amps. I am quite happy with this lateral move. Both are Class A so the heat issue is a wash, and both accomodate tube preamps with relatively high input impedances of 47K for the Lamm and 100K for the Clayton's. The M1.1's sound great but are an older design, a bit dark in tonality and somewhat rolled off in the HF. The Clayton's do not suffer the darkness or HF roll-off shortcomings, provide more power (200wpc into 8 ohms and 400wpc into 4 ohms), are a newer design with newer output devices, and came with a warranty. There are some things the Lamm's did a bit better - if you like a darker, richer-sounding presentation, and they were maybe just a touch more dimensional (due to the tube in the input stage?), but both kick strong in the bass and I don't have to consider changing tubes with the Clayton's. The M200's double into 4 ohms and drive my 90dB speakers to very satisfying levels, where the Lamm's did get a bit "hard" sounding when pushed to levels I would not normally listen at. For true Class A solid state, you would be hard pressed to do better at similar power levels than the Clayton's. They also offer an M300 mono pair with a low bias switch so they can be left on all the time. All that said, the newer Lamm M1.2's would be very high on my list to audition, if I had the cash.