Hi. can the pre amp be stacked up with the P5 and direct stream jr? Or is there a minimum space needed for ventilation?
Check the manuals, the P5 probably puts out a lot heat, I know my P300 sure does. You have over $13,000 worth of quality gear, invest in a bigger rack or add another one. Audio Advisor sells a 4 shelf Pangea rack for $100.
If you do stack them get some kind of disc to protect the top surfaces, even just some soft cloth cut to size, and then something reasonably tall. Hardware stores sell rubber stoppers in various sizes that work very well.
But, only stack them if there is no other option.
To expand on Jeff’s answer … First off the basic chassis for the P5, DS, DMP, and BHK Pre-amp are all the same (with minor variation for ventilation) and were designed for stacking. You can even remove the feet for tighter stacking. Having said that, the answer depends on the component. The DS and the DMP can stack without heat issues, though most folks here will recommend you keep them separated for best sound. The P5 does generate some heat and does have ventilation holes on top so they should not be covered. The BHK Pre-amp has ventilation holes on top for the tubes inside and definitely should not be covered up. As such stacking is probably not a good idea, but if you must stack put the hottest component on top and use some sort of spacer, preferably a vibration isolating/controlling device between components to separate them and monitor how hot they get to make sure they have sufficient ventilation.