I know I've started a lot of threads trying to diagnose my problem. Sorry about that. This forum has been very helpful so far. Thank you to everyone for your help!
In case you haven't experienced my needy nature yet, here's my problem:
My receiver (Marantz SR5003 [6 ohm]) is not properly rated for my speakers' (Polk LSi9s [4 ohm]) impedance. It works perfect for music but when I watch movies, the very low bass tracks cause my receiver to go into protect mode (or even blow) because in the low bass region is where the impedance for the speakers drops especially low which causes the receiver to draw too much current to handle. Originally, I wanted to buy a separate external amp. Then I thought about selling my receiver and buying an external amp to replace it. My source is my desktop computer.
However, I've decided against these two solutions since the first one is too expensive for me right now, and the second option forces me to use my computer's DAC which is severely lacking. I've even tried using an M-Audio Transit as my DAC, but nothing so far compares to the receiver's sound using optical from my computer. Using the 3.5mm jack on my computer or the Transit simply makes the bass way too wimpy and the highs overly bright. Bright enough to cause listener fatigue.
So, in the effort of preserving the sound quality the Marantz puts out using optical and finding a low cost solution I've come up with these ideas. Let me know if you think they are valid:
1.) Since it's low extended bass that causes the receiver to go into protect mode - buying a stand-alone crossover with a step high pass filter that cuts off around ~40 Hz.
2.) Is it overheating that is causing the receiver to go into protect? If so, could I come up with a cooling solution using fans or even possibly water cooling?
3.) Somehow increasing the resistance of the speakers? High resistance wires? Installing a resistor in-line with the speaker cables?
4.) Somehow installing a current meter so I can watch the amperage and adjust the volume accordingly so I don't push my receiver too hard. I feel like I'm totally blind figuring out how loud is too loud. I can easily watch movies at moderate levels, but as soon as I turn it up too much, (and depending on the bass track of the movie) it's a toss-up of whether the receiver goes into protect or not. It's happened at +4dB, -5dB, even -15dB once.
5.) Installing some sort of current limiter? Do these exist?
6.) Any other suggestions?
I know what you're thinking: Wow, what a cheap ass! Just buy a cheap, used, external amp! But I'm a poor college student who simply wants to enjoy the loud, stunningly realistic sound from my LSi9s and my Marantz.
Sorry for the long post, but please help me out! Thank you so very much!