It sounds as if your new preamp has lower voltage gain than your previous one. Yes, the preamp can affect the output of your power amp as it amplifies the signals from your front end so that it can be used to drive your power amp. There is nothing inherently wrong in using a higher volume control setting unless you start amplifying noise. If your preamp doesn't have enough gain, however, it could not drive your power amp to full power. Going to a higher-powered amp may not necessarily cure the problem. Going to a power amp with higher voltage gain, even though the ultimate power output may not be higher, is probably the solution you are looking for. If your disc player or phono preamp has variable gain you could increase the gain on these to account for the lower voltage gain of your preamp.
Changed preamps. Seems like less power now?
I recently changed my preamp from a Rotel 1070 to an Anthem TLP-1, and have noticed that my system seems to have less power. I have to really push up the volumn to get any decent high levels, where is with the other preamp, it got very loud easily. Does a preamp effect the output of the power amp. I don't know if I should change it back out, or maybe go with a higher powered amp. I run Thiel CS.5, and they seem to be hard to drive compared to some other speakers I have owned. Thanks for any help