Maybe a dumb question about preamps

I am considering to purchase Bryston 4Bst or 4Bsst. Do you absolutely need to connect them to a preamp or can they run by itself and still achieve the sound quality that they are intended to produce. If preamp needed, would it be appropriate to connect to a Pioneer Elite 52TX that I have and use it as a preamp. Thanks for your advice.
Well, here's a dumb question as well. What are you going to connect to this amp? Does it have an attenuator?
As Newbee points out, the answer depends on whether you already have a way to control the volume and to switch between source components (if you're using more than one). If you have an attenuator in the amp or in your source component, that's one piece of the puzzle possibly solved, although there's still a question of the sonic quality of the built-in attenuator versus one that would be in a good separate preamp.

If you have multiple source components, you can either plug and unplug the interconnect cables at the back of the amp to change sources (lots of wear on the connectors with this approach) or you need some switching capability (this would be provided by the preamp).

If you're OK on these points, there then is the question of whether your source can drive your amp to full output (some may be able to, others cannot - you'll hear this in the dynamic range of the output from the amp). For lot's more information, search the archives for "passive" preamps and linestages.
On the other hand, if your source doesn't control the volume then use your Pioneer's ''Pre Outs'' and use it as a Preamp.
Foxtrot; That was toooo easy;why didn't I think of that??
The Bryston 4BST is connected to the pre-out from the Pioneer Elite for the two front speakers with Music Hall CD25 for music, Samsund DVD for HT. I have to use the attenuator from the Pioneer or else the sound clips even at low volumes. Any better suggestions for hook-up or components that I may need to add to obtain better sound quality from the Music Hall, Bryston amp and Pioneer pre-out? Thanks again for your suggestions.