Hi there, I currently have an Ampeg PF-350 head that I run though a Peavey 410 (300W @ 4ohms). Everything works great. The only problem is that my band just decided to have both of our guitarists each start playing in stereo with two cabs a piece. Thus, my little 410 is no longer keeping up volume-wise. I purchased a great condition vintage Ampeg cab that has -strangely enough- two 15"s AND a 10". I'm not sure if it's a custom build or just some random model I cannot find any info about on the web. There's one input jack on the back of the cab and the plate above it has the Ampeg logo and "4 OHMS" on it. The rest of the plate's info is worn off. When I hooked up the new cab with my PF-350 with the master volume and gain both set at 5, the cab's volume isn't half what the same settings produce with the 410. When I increase the volume on the head to about 7, the signal starts cutting out intermittently. My initial thought is to upgrade to the PF-500 and hope that the extra wattage will solve the problem, but after perusing the web for more research I'm now learning that the cab may be the problem? I do not know the cab's RMS rating. So, my questions are: 1) How can I test the RMS of the 2x15+10 cab? 2) Is the head the problem due to volume distribution? 3) Could the cab just be in need of repairs? Thanks everybody. PLEASE HELP!!