Imagine that a pro quality recording is the water in a flood. The “greater quality” the song, the more land it devours. So a super “quality” recording would look like something you can only read about in the Bible. It would cover most of the world.
In our analogy, we are going to pretend that there are protective levies in place to make sure we don't devour the entire world with our amazingly “pro quality” recording. You can see, we have 5 different barriers blocking us from our goals of taking over the world with our high “quality” recording.
#1 – Song / Musician / Producer
You'll notice that this a tall barrier. In fact, it's extremely tough to beat this barrier. Basically, if we don't have an amazing song, the best musicians in the world, and an extremely talented producer, we will not go over this wall. This wall represents the creative side to the music. When a tremendously talented musician and producer get a hold of a great song, it can be truly magical thing. The focus here is the talent of the producer, musician, and songwriter.
It's important to note that a person can be all three and you can certainly do all 3 of these things at home. It's not like you have to be part of some Nashville union to do this. The band themselves can be the producer. This is fine and normal. If the band is talented enough at producing, they'll get what they want. If the band isn't talented enough at producing, then the “quality” of the recording will not be great enough to overcome this first barrier.
Think of the worst singer you know. Maybe it's you, maybe it's your brother, or maybe it's one of your parents. Imagine them singing a song in a high end recording studio. Of course, we know that the right producer can often make a person sound great. For strong evidence of that, check out the Paris Hilton cd.
#2 Audio Engineer
You'll notice that the great audio engineer doesn't even make a difference unless the song, musician, and producer are all great. We are referring to the skill of that audio engineer here. You'll notice that the first two barriers are people (and their respective talents).
While many times a producer is a great audio engineer, its generally a practice to pay an outside engineer to free up the producer to focus on the creative side of the music. So it's possible, that the songwriter, musician, producer, and audio engineer could all be the same person.
Hiring the right audio engineer is important. We've all heard bad recordings come out of huge studios just as much as we've heard great recordings come out of home studios. Assuming that the songs and performances were great, it's the audio engineers job to make sure the recording sounds great.
#3 Room Acoustics
The room an instrument is recorded in makes a tremendous different in the “quality” of that recording. Clap your hands in a bathroom and then clap your hands in a closet. The difference is tremendous, but it's up to the song to decide which one is best. There are more things going on that just the obvious reverb adding to the sound of our clap. Some room support low end better. In that, I mean that close mic'd toms will sound better in certain rooms.
The room because a part of the instrument. This is a huge deal for drums, orchestral instruments, and any instrument that doesn't usually sound dry.
Of course room acoustics are meaningless if the song sucks, the musicians suck, or the producer sucks. It takes a special audio engineer to know how to shape room acoustics into what he/she needs for the song.
#4 Recording Gear
Yes, I know. The recording magazines constantly talk about gear. The online forums constantly obsess about gear. Well, I've got some high end gear. It CAN help make a difference, but I have never seen a $3,000 microphone that overcame shortcomings in the song, musicianship, or producing. I've never seen a great mic in the hands of a terrible audio engineer do any good either. I've never seen a $3,000 microphone overcome a terrible sounding room or a room that is wrong for the song.
Yes, I do think recording gear is important, but I would NEVER choose expensive recording gear first. I would choose to work with the best songwriters and musicians I know. I would work my ass off at producing and I would pay a real engineer to produce and I'd take the band to a mega studio with mega acoustics before I shelled out $3,000 for a compressor.
I think the concept of recording gear is overstated simply because there are companies that are willing to buy advertising space. I also think it's much easier to talk about the a 1176 compressor than it is to talk about the technique where you use drum underheads instead of overheads. By name alone, 1176 is one word. “The-technique-where-you-use-drum-underheads-instead-of-overheads” is pretty much a sentence in itself. It's just harder to talk about techniques without actually being there in person.
#5 The Weather
Okay, this doesn't mean if it's raining or not. I'm referring to the things that are out of your control. While this can be thunderstorms and snow, it can also be the singer getting sick, the frigerator not working, or your hometown being sold out of Red Bull's.
If I ran out of coffee, it would drastically effect my ability to produce music. (I always get jacked up on coffee before a big session...ALWAYS!).
Conclusion
If you can beat all 5 of these barriers, you will make a “pro quality recording”. The odds are strong that you won't get passed the first barrier. It is, by far, the hardest to get through. Once you have great music and musicians, you'll find that it makes more sense to go to a big studio and hire an engineer.
If you are worried about a piece of gear being “pro quality”, you may need to rephrase your question. Many huge songs have used ridiculous gear. I'm talking about toy ray guns, Radio Shack microphones, etc. I'm sure that a cassette deck boom box recording has been used on some huge hit song. What made all of these songs great was not the quality of the machine using them, but the magic of the sound that went into them.
In the end, the gear is just a tool. Some tools make it very hard to make a great recording, other tools make it much easier. If you are not sure, just ask on the home recording forum? .