Can I get a

Hello Everyone,
I am overwhelmed and intimidated by my choices and I need some expert help. Let me start by stating what I'm trying to accomplish. This is for a really good friend of mine, who's a musician, a bass player. His birthday is coming up in April and I've convinced some friends of mine to go in with me on buying him a stereo that is worthy of him, and his music collection. He's a hard-working guy and deserves it.
So this is what I'm trying to accomplish. Create a system for a 12'x10' room, using "bookshelf" speakers with a subwoofer, 2.1 or 5.1, I don't really care. Logic would make me think that 2.1 speakers for the same price as 5.1 speakers would be better because it's more expensive per speaker, but I know the world isn't all that logical. What I do care about is bass response. Something that has low frequency response in the bookshelfs (bottom end of 40-45hz seems to be the limit), but I want the subwoofer to get to 20hz. Am willing to settle for 21hz :)
His primary music of choice is metal. And not like Judas Priest or AC/DC metal but death metal, black metal, and grindcore. Yes he likes Iron Maiden too. I know that from my readings of audiophile magazines back in the day it seems like there's a predominance of classical music lovers that populate audiophile ranks, and for those of you wholly unfamiliar, the music of this extreme metal is analogous to classical, just with heavy, heavy distortion. I say similar because there are often many instruments in the mix, and they are playing technically difficult pieces at high rates of speed, and separation of instruments is just as important as being able to feel like the violin and woodwind sections aren't smashed on top of each other but have some space on the "stage". His second favourite genre of music is classical in fact, but it is a distant second.
I love music myself and have considered myself an audiophile in spirit more than in practice, reading "Stereo Review" magazines as a teenager and absorbing every word, but I didn't keep up with it. I know some terminology from when DSP was just coming into existence in solid state amplifiers and receivers and HDMI was merely a gleam in some engineer's eye. Also I know that some things - like cassette decks - were made better 20 years ago than they are nowadays, but has everything else been improved upon? I know that my money will go further if I buy used equipment to compliment perhaps some new equipment, but knowing the huge pantheon of equipment out today along with what has been out there for the last 30 years has made my brain spill out on the floor more than once.
What I'm looking to buy:
1. The receiver (or power amp, pre-amp, phono stage amp) Contenders were a Denon 3805 if I just wanted to keep this as a stereo and not connect a TV to it, Arcam AVR360 used? I had a receiver back in the early 90's that had a THD of .005% (I looked it up just to be sure) for stereo so I'm kind of surprised to see that's still about what the receivers of today can also accomplish. Watts, my early receiver that I mentioned before had 125w/ch, the Denon has 120 at 8 ohms with low THD, but I think it does HDMI in some archaic way, hence being hesitant to hook up a HDTV to it? Also I don't know if I might need some unusual speaker connectors depending on the speakers that are selected...
2. Turntable. This is about the only thing I feel fairly comfortable with the choice so far, but I'm certainly open to hear why I'm wrong, my choice is the $400 darling of the press, the Pro-ject Debut Carbon.
3. Cassette deck. Yes he's got a lot of demos and stuff that's ONLY on cassette, would be good to have the best source possible for an eventual digital conversion. My thoughts are to stick with something that has Dolby S and 3 heads, with the latter being more important than the former, like something from the Sony ES line in the mid-90s or something I actually have personal experience with, like an Onkyo TA-2600 (is there a newer version?) Nakamichi Dragon anyone? I feel like I can get something in the $100-200 range here.
4. CD player / DAC for digital media (MP3s, FLAC) Ok, why did I group them together? Two words: the Oppo BDP-105. It would be almost half the budget right there (I might be able to get it for about a grand flat) but from what I understand this thing will put hair on your chest while blowing it off your head! Undeground metal never got released in SACD format and blu-ray audio seems equally unlikely for this genre of music, but it supposedly really does a number on upsampling of CDs, and is supposedly a preeminent DAC for the aforementioned sound files on a computer. He actually doesn't have a lot of these but I figure if I can kill two birds with one stone and future-proof it simultaneously, it's a win-win-win. Otherwise, I know nothing about DACs really, I saw the Essence HDACC, Emotiva XDA-2, they look good, are they? Back when I bought a component CD player things that were important were a high S-to-N ratiio (105db+ was considered very good), oversampling at a minimum of 4x... Yes, I've heard of CD transport through tube but have never seen it in real life.
5. Finally the speakers, what do I know other than bass needs woofers and woofers need space? I've seen speakers that have two cable inputs, marked HF and LF? Do those work with regular receivers or do they need some kind of discrete crossover? I'm really overwhelmed here, the only thing that I've seen that had good subwoofer ratings were the Monitor Audio MASS 5.1 Speaker System and the Definitive Technology ProCinema 600, I know a dilettane's research to be sure, but I have a job too! Both of these are probably better for home theatre than music, but not bad? This is a place where I think I could really use some help from the community to school me to some speakers where stereo reproduction is the main consideration.
5a. Cables and interconnects. I was pretty deep into the religion of expensive audio cables about 13 years ago, but I'm in IT and I had a revelation one day, which is that if an audio signal has some data distorted the note may sound flat or sharp (an exaggeration I know), but if a cable carrying data puts one byte out of order, the file will be corrupt. In other words, the necessity for perfection is much higher in computer land, and yet $2 SATA cables for hard drives, and $5 USB cables, can send terabyte after terabyte of data back and forth to the computer with no corruption. So $100 cables, nevermind $1000 cables, just another re-enforcement of the old axiom about the fool and his money? Please let me know how this comparison is wrong and I'm the fool.
Finally, just to be clear, if I could do it RIGHT, I would like to be able to deliver a stereo that could connect to a HDTV with a cable box and a Roku, and output the sound to the stereo, maybe something like the Denon 3805 I mentioned earlier would do a splendid job of this? I'm out of it with these HDTVs because I don't really watch (crazy I know, I <3 the music more) I truly apologize for being long-winded, but I've learned the devil is in the details, and in the many posts I've read I see over and over again, people ask what genre of music will be predominantly played. Thank you so much if you've actually read all of this, and I want to thank you all for helping me make my friend's birthday one he'll remember for a long, long time.