richie, all great points.
The 3K has been glorified for a number of bad reasons, 1). J Dilla/Dr. Dre are its poster children; 2). it was Roger Linn's last MPC (and with that brings into question a sense of solidarity or even trust when we are talking about Akai as a brand after dropping him); 3). the illusory "swing" and "feel" the machine seems to exude into the minds of its users.
It is common knowledge that the 2K and 2KXL are functionally "upgrades" from the 3K, but are sonically "different" and in some people's opinions "downgrades." (I happen to believe that all three sound very different but also very wonderful.) Structurally, the 3K is considered to be "better built," however I find both the 2K/XL to be built with much higher quality components than any of the NuAkai products. Certainly the 3K feels more "dense" in it's build, but the 2K/XLs are also tank-like in their own way.
It is also commonly known that 3K's swing function being superior is pure myth. The MPC quantize algorithm digital and functions the same across the board. This "feel" the 3K seems to have must be psychological, or maybe from a certain interview I recall with R. Linn discussing what made the 3K so good in his opinion... Regardless, quantization is simply fractions and ratios of time passed between midi events; basic arithmetic cannot be "cheapened" when they are put into an affordable unit like the 2K in 1997... This is a myth.
Thus I have the same feeling as richie, that possible the only functional benefit to an 3K over any other MPC is its distinct (not more fidelitous) sound. The 3K sound is coveted because it is culturally associated with the sound of the '90s/early-'00s hip hop generation, not because it is technically any "better" sounding than a 4K or Z4/Z8 engine, or a S5/6K, or debatably the 2.5K/1K/5K range MPCs... When 3K users discuss the "superiority" of its sound, they are also stating their alternative bias towards a technically lower-fidelity sound over a higher fidelity sound; and for them it usually has to the 3K's sound or the SP-1200's sound, and not the lo-finess associated with the 2K/2KXL for some reason... So even the sonics of the 3K are not necessarily "the best"; they are simply the best at sounding like a 3K––and thus like Dre, Dilla, etcetera. (Speaking of star-power, lets not forget that the 2KXL boasts users such as Pete Rock, Kanye West, and Madlib... some of hip-hops most revered producers. Again, the 2K series simply offer a different mode of lo-fi sound for the modern producer.) Let us remember that what makes the older samplers sound so "good" is actually how "bad" their convertors are (just as the 2.5K/1K/5K range MPCs sport convertors that are "bad" in a different way).
And bad is good, generally!!! I would assume there is a healthy, 50/50 split between users on this forum looking for that "good-bad" sound, and others looking for that "clean-sterile" sound... Breaking sonics down into these two very crude categories is common practice in the online sampling community, but does not actually address much about freq. range, bit depth, convertor quality, etc. The 2.5K/1K/5K MPC series sounds MUCH "cleaner" than the 3K/2K/2KXL MPCs, despite having the "same" specs (16-bit, 44.1kHz audio). However, I would bet that most people on this forum would prefer the sound of the latter three of the aforementioned units.
The point being, the 3K is a great machine hands down, but the cult of superiority surrounding it does not have much ground to stand on when we look at the facts: The 2K/2KXL blows the 3K out of the water, functionally. Sonically, they offer something different (for some undesirable, for others coveted) than the 3K. However, the added features of the 2K/2KXL cannot be replaced by a rack mounted unit... whereas the 3K's one true merit CAN (as richie states above). It just makes so much more sense for the modern user who NEEDS the 3K sound to purchase literally any MPC following the 3K (minus the 500) and sequence a 3K series rack sampler with it. Increased workflow with NOTHING lost from the 3K in that regard + the desired sound for the 3K lover, all generally for a price less than or equal to buying a an MPC 3K. [I bought my first MPC 1K for $450 and my S3200XL for $350. I bought my MPC 3K for $800. I see clean 2.5Ks on Craigslist going for as low as $550 now, and S3000s for less than $200, whereas I see oatmeal-chassis MPC 3Ks going for $1200+, and 3K SEs going for $2000+.] All the machines mentioned (minus the 1K) can be expanded or come pre-loaded with the 8 output option. The 2.5K/5K/4K all have the same amount of midi outputs as the 3K. All have tons of tactile controls like 3K.
Now to the 4K, my favorite piece of digital music gear ever created (next to the Nord Modular G2X). How can it be compared to the 3K, when it is so much closer in function to the 2KXL? The 3K and the 4K are competing for two very DIFFERENT spots in the MPC/sampler hierarchy... The 4K has the HIGHEST fidelity audio of any MPC or other groovebox... Does this mean it sounds the "best"? NO! Not to everyone! It simply excels at sounding the most faithful to the sample source compared to its competition. Can it sound like an MPC 3K? NO, but also YES! Yes, only if you resample through an 3K series sampler; no, certainly not without a 3K series sampler to resample through... Because only 3Ks sound like the 3Ks! If YOU think the 3K sounds the "best," the 4K will not sound as good to you. To me, I like the 4K because I can resample audio via ANY of my samplers, even the grittiest of the grit (like my S6K set to 8-bit depth, resampled through my S700 at a 4kHz sampling rate), and send the finished result back in the my 4K and viola, it sounds EXACTLY like an 80s Akai sampler... because the 4K captures virtually every nuance of whatever audio is outputted from its lower-fidelity counterparts in my studio. Then on the next track, I can have a crystal clear sample of an acoustic instrument that is properly mic'd and record D.I. into the 4K. Basically, the 4K's fidelity offers headroom, flexibility, and reliability. With a 4K, you have the MOST control over what you are capable of creating sonically, assuming you have other vintage gear to crush the audio down however way you take it, or nice mics to capture hi-fi audio. Buying a 3K is, to me, is like purchasing a nice, sonic template that all of your tracks must adhere to... And if that sound works for you EVERY time, then great! Stick with the 3K! You can sculpt the sound with your outboard gear or in your DAW later anyways. The 4K will offer you the option adjust your sound as needed based on what you decide to put into it––in other words, sonic flexibility starts on the level of the sample itself with the 4K.
The 4K also has a superior sequencer to the 3K. You can find the specs easily online and compare them. The 4K can give the illusion that no quantization is being used on a particular track, because its sequencer's resolution is literally 10x as fine as the 3Ks. However, it can also quantize as strictly as a 3K. Headroom and functionality is only gained by upgrading to this sequencer. Ease of use out of the box is another story, but those who have mastered both machines will be able to DO more on the 4K sequence-wise, if desired.
One feature only the 3K boasts is the ability to connect an external display to increase the text size of the screen... This may be a selling point for those comparing a 3K to another pre-2002 model, however as we all know, although the 4K's display cannot be mirrored directly onto an external display, it has an even BETTER function... ak.Sys... which does not simply mirror and enlarge the text onto an external display, but provides an extensive editor for the 4K with which users can access multiple screens simultaneously when connected to a computer running the proper OS. It is not like the MPC software at all [in that you still have to touch your MPC to make a beat
], but is complimentary to the unit's physical interface.
These are simply the three most significant advantages to the MPC 4K. Each could be considered disadvantages to the dedicated 3K user... cannot get genuinely vintage grit out the unit without something to resample through; the complexity of the sequencer steals away from the "groove" that comes so naturally on the 3K; the gross advantage of ak.Sys takes away from the 'in-the-boxityness' (self-contained nature) of the 3K... I personally choose to see them as major advantages because I HATE automation and I LOVE retaining whatever degree of agency I can over my creative process; the 4K gives me the flexibility to allow my head to dictate the process, rather than making decisions for me like the 3K. Sometimes I WANT to hear a crystal clear sample of an actual acoustic snare drum, and I want that sample to include all of the highs and harmonics that can be lost in the 3K. I don't ALWAYS want to sound the way the 3K sounds... sometimes I do! But certainly not all the time... Sometimes I WANT to perform my drum tracks live and retain all the inaccuracies in my human performance, even if it means no two bars in my beat sounds EXACTLY the same... the 4K allows me to do that very nicely, while also providing plenty of quantization control when needed. And SOMETIMES, I love just sitting down with a 4K and not using the ak.Sys and staring at the little woman tapping her foot and crossing her arms as I wait for things to load. But I also SOMETIMES like to hybridize my workflow with the computer so that I can the results I want more quickly and accurately.
In effect, the MPC 4000 can do EVERYTHING the MPC 3000 can do, except generate the 3000's tone from scratch. In can, however, sound exactly like an MPC 3000 if you have a 3000-series sampler to resample through, or even to sequence via MIDI. Furthermore, the 4000 can do all that and MUCH, MUCH more than the 3000 can. The 3000 could MIDI control a Z-series sampler and sound like a 4K in this manner, but you'd still be missing the power of the 4K's sequencer.
I think I merely succeeded in belaboring the gist of richie's points, so my apologies if you did not learn anything new from me, huh?. The USB port and turntable pre-amp functionality is nothing unique to the 4K, as most of the modern MPCs have these features and much more. If we're talking FEATURES, 3K is lacking compared to almost every one of its successors. If we're talking SONICS, the 3K offers something unique and coveted but certain other MPCs and samplers offer unique and coveted tone as well. If we're talking SPIRITUAL connectivity, at the end of the day, no MPC model happens to have a port or jack for that... we only see illusions or spectacles, hear myths, or brandish commodity fetishes.