Newbie wiring amp and speakers to stockHU

I have a 1992 3000gt and I am wiring up an amp with component speakers in the front and a sub in the back.  I'm keeping existing rear channels from the stock HU.

My plan is to run speaker level inputs to the AMP (Power Acoustik PA2-300 2x70w RMS) for the left and right front channel.  The amp will then power two infinity 605cs component speakers with their own crossover.   Then I want to hook a DVC sub to each channel. 

a) will this work (I know its not perfect, and if it doesn't sound good I can always adapt the HU down to RCA out for the AMP)

b) should I wire the sub and speakers in parallel from the amp to present a 2 ohm load to the amp, or should I use a HP/LP crossover and send the lows to the sub (below 120Hz) and send everything else to the crossover for the infinity speakers (This would present a 4ohm load to the amp- I think)?

I'm not looking for huge power, just good, clean sound with a deep bass to round it out.

You are using the "HI INPUT" on your amp? instead of RCA cables? And i'm not familiar with Power Acousitik products but is that a 4 channel amp? So you are planning to run a DVC sub and a set of components off the same amp? Because don't you need at least two channels to run your speakers and another to run your sub?

If it is a 4 channel, run your speakers mono and bridge your sub and give it some more juice. (Hopefully someone can tell u if that amp has enough power or not cause I dont' know by what your running). If you're looking for better sound don't bother running it in parallel cause i find that the bass isn't as nice in parallel as it is in mono, but doing it in parallel will always give you more power.

If it's a two channel amp I can't see how you're going to run speakers and a sub off it.

Heck, you should just get an aftermarket HU. But hopefully someone will be able to give you better info than i did. It wasn't the best. But i'll check it out after I get back from work.

Hi input - yes (for now anyway)

2 channel amp

As far as how to run 4 speakers off two channels:
I was planning on running 2 4 ohm speakers on each channel (in parallel) for a 2 ohm load
                              -or-
using a crossover to run the extreme lows to the sub and the rest to the full range speakers

Just answered a question sort of related to your situation.  If you have a 2 channel amp that is 2 ohm stereo stable, that means you can actually hook up 4 4 ohm speakers safely.  You wire two speakers in parallel for each channel, for a 2 ohm stereo load.  Here's a lil more info on series/parallel if you're interested...

https://www.eatel.net/~amptech/elecdisc/spkrmlti.htm

But as for your situation, I couldn't tell if the amp you have is a 2 channel or a 4 channel amp.  Let's assume that it's 2 channel.  I'd recommend against running 2 component speakers and 2 subs all on a 2 channel amp.  Because you'd have to use separate crossovers for the subs and the speakers, you'd present a whole bunch of potential problems.

a passive crossover will actually decrease sound output, especially one with a high slope.  This is because they are wired in series with the sub and increase the total resistance the amp "sees." So the power output is less.  Sometimes the difference is very obvious, sometimes it's not so bad.  Depends on a lot of things, including what materials are used for the crossover, what slope/cutoff frequency the crossover has, what impedence it's rated for, etc.

Usually I only recommend wiring each channel of a 2 channel amp in parallel when you're using identical speaker types (i.e. all subs or all speakers).  Or if you have a 4 channel amp you'd use front channels for just speakers and 2 rear channels for just subs; because most 4 channel amps have separate built in active crossovers for the front channels and the rear channels.

Although there a lot of active crossovers that will accept both RCA and speaker-level signal inputs, they all only give you an RCA output.  The speaker-level inputs are only there to allow you to hook it up to a head unit without RCA preouts.

I found this page cached on google and you might want to check it out, it has a lot of good info about passive vs. active crossovers and probably can explain stuff a lot better than I can.

https://www.google.com/search?q=cache:lAxp95NA_HAC:www.termpro.com/articles/xover.html+passive+crossover+chart&hl=en&ie=UTF-8

I spent a good 12 hours wiring it all up today.

I got it all wired up and working but I have the following problems:
Whenever the amp is on and the radio is not, I get a REALLY loud buzzing in the passengers speaker.
(I can't use the antenna lead because antenna is only up when am/fm is on, otherwise off, so I have the remote turn on wired so that the amp is on when the car is on)

Whenever the amp is on and the radio is not on, I get engine noise (RPM related whine).  (Power cables are run seperately from speaker cables.)