Greetings "Tcpip",
There was a loudspeaker company (they might still be in business) that built a minimonitor that could play faithfully down to 35 Hz @ -1.5 dB. I know this was true because I had auditioned this rather amazing minimonitor, especially considering it only had two 3" mid/woofer drivers to do this with, and it still was able to accomplish an 87 dB sensitivity rating. Is was from a company called Digital Phase, and the model was called the AP-.7. I believe that the website is still available at http://www.digitalp.com. If not, you might do a search on the internet or here on AudiogoN for them.
A few that are currently available from companies like Talon Audio (that has a large rather expensive monitor that plays below 20 Hz if I remember correctly), Silverline Audio, and Paradigm I believe still has an active monitor that goes down into the low 30's.
Hope this helps you some.
Authorized dealer for http://www.SilverlineAudio.com
Best regards,
-Donald
http://www.wenterprisesnw.com