I don't know dude, I would go with components. I had some MB Quart reference 5x7's for awhile... they were alright. Then I installed some 6.5" components from PG and holy crap... they sounded elite. But back to your question... I very highly doubt any 5x7 speaker is going to produce a 5hz tone well. Actually, I can tell you flat out, they won't. I think 20hz is fine for a low end, I have the eq on my amp cutting off stuff that low to my front speakers. All that low stuff is make them bottom out for me. I'd get a nice sub to fill in the bottom end if you are really worried about those low frequencies. Also, I think that headunit will be fine for powering speakers. I ran those quarts off my eclipse-5441 for a bit and they sounded okay. An amp would help though, there was a huge difference once I added an old school orion cobalt amp. Good luck!
