Not having a Subsonic filter is certainly not a deal breaker... In a sealed box, most will never need one. In a ported box, it would depend on your tuning frequency. In an IB setup, they may help, but certainly not NEEDed.
If you feel you must have a subsonic, but the amp you like doesn't have one, simply do this.. Line Level Crossovers
Why pay $100 more for an amp just because it has one built in?

Sweet, thanks man.

Well I think I got bit by the mod bug. Do you got any recommendations for door speakers under 300? I actually like my Polk Audio DB6501 and I listen to most of my music using google play on my phone linked over Bluetooth.

I'm thinking of getting the Image Dynamics IDQ12 for my sub.

Are you looking for coaxials, or component sets?

Do a component set and you can certenly find some good sets for 300 bucks. CT sounds has made a good impression on me recently, Hertz has another great set, as well as focal and MAYBE Image dynamics if you can find them on sale.

https://www.amazon.com/Sounds-Meso-6.../dp/B00TRKNODO

https://www.amazon.com/Hertz-Audio-C...keywords=hertz

https://www.crutchfield.com/p_091165...hoC9lIQAvD_BwE

So I returned the kenwood and ordered an Alpine 5 channel. My old PPI 900.5 sounded much better than the kenwood but that could be cause I had the kenwood bridged.

Will the alpine amp produce less heat at 2 ohms than 4 ohms on the subwoofer channel? Itll put out 500 watts either way.

Also I'm gonna order the IDQ12 and was looking at zenclosures. Astheticaly I like the rearfiring but the upfire has slightly more space 1.18 vs 1.35. Optimum is space is 1.8 cube ft. Is the extra .17 cubes gained from upfire config gonna help make it sound better?

Will the amp produce less heat at 2 ohms vs 4? Likely more heat.
Will the extra cu ftage gained make an improvement in sound? more than likely, but possibly not enough to hear the difference. Adding polyfill to the enclosure will improve things for you. 1lb per cu ft.
It causes the sub to react as if it has more air volume than there actually is.
Most say a 10% increase, some argue higher.
Dont forget you need to deduct the space your woofer consumes from your total box volume as well.

Thanks, bro. The amp has made all the difference; waay better sound quality and way louder. I'll probably go with the upfire config and polyfill just to squeeze out a little extra SQ.

I have 4 channels to work with from the amp. I've read that active crossovers are better than passive. Would I get noticeably better SQ by running my tweeters and woofers all to separate channels and using the amp as a crossover (hi-pass filter) instead of the passive crossovers? How do I find how much power to send to the tweets vs. woofers and what crossover frequency to use for each?

Active crossovers are considered to be better because of the amount of control they give you over your seperate components, as well as the small amount of power loss that is adherent to using passives.... A true active setup must come through a processor, whether it be outboard, or built into your head unit. using the crossovers on your amp, in my opinion, is just not worth the effort it takes to set crossover points correctly, as well as levels, for your particular speakers. the passive does all that for you, at the points the manufacturer recommends for the speakers.
Without processing, I'd leave the passives on.

Thanks man I'll probably leave as is unless I get a dsp.

One problem I'm still having is that my amp is burning hot when playing. I've checked the ground for resistance and its good. I'm at a loss of why? Intuitively I just feel that the amp is too hot for just running two channels. People always talk about cool class D and this is uncomfortably hot but no therm protect. I know the gains I set are under what they should be because I checked with test tones and it is still a humm and I never even went close to buzz. When the HU is on pause I hear slight white noise through the speakers that I didnt notice before. I dont know much about amps but I would expect them to be near silent when not playing music. *sigh* third amp and most expensive ive spent way too much on amps on this car.

I replaced all my RCA's recently. 4 guage wiring from knu konceptz and UL cert 16 radioshack guage wiring for the speakers.

What should I check?

Hmmm. heat issue seems odd for a class D amp. You may want to contact whomever you bought it from, or the Manufacturer with that one.. But speaking of DSP's, Give this a look....... https://www.parts-express.com/dayton...audio--230-500
New on the market, and the price can't be touched! I just ordered one to put on the shelf in the garage. Hey, you never know when you're gonna need an extra DSP unit....lol

Where is your amp located?

underneath driver seat

https://imgur.com/a/gWyLnoO

it sits on a ridge and front is velcroed in place so the entire bottom is not touching the carpet, there's a very little airgap on the bottom.

https://imgur.com/a/gWyLnoO

https://i.imgur.com/uv0w1BV.jpg

I think I'll just turn it on for 20 min with the seat forward like that and see how hot it gets.

So now my passenger door speaker is blown so I unplugged it. It still gets hot not warm after playing but not as scorching. It was pushing just one speaker at 2/3 voluem

I set the gains to V=sqr(100watts*4ohms)=20V using 1khz tone.

The passenger speaker is blown. Either that or the amp is putting out distortion. I had it on high volume and then backed down on the volume because of distortion but it is blown. The driver side one sounds fine. The driver side one is the older speaker.

I'm kind of scared to damage the amp since its kinda expensive when you're a college student. :shakes head:

So far the ground reads near zero resistance and that's checking from the end of the cable that's connected to the amp. I took a DMM and measured the resistance between the ground cable and the negative battery post and it was really low. The ground looks good it's tightly held in place.

I retightend the crimps using an actual crimping tool today.

I moved the ground to a better spot with a bolt that I sanded down. The bolt and spot was painted so I sanded it down some. It still gets warm fast so I will sand it some more just to be sure.

I'm going open up the door panels to make sure the wire connecting to the speakers is properly fixed in place.

I honestly don't think these are the issues but I have no idea what it could be. Maybe this amp is just supposed to run hot?

Do I need a spacer for these: CT Sounds Meso 6.5 Inch Component Speaker Set?

Yes you will need a spacer for those.