Superb option are the concerts in various local churches and other small venues. Although in churches the acoustics are not always great, what you do get is much more intimate atmosphere, you can get much closer to artists.[/QUOSo well put. My experience is the same.
I grew up singing in madrigal groups and choirs at school (wasn't entirely happy about but it taught me to love music). I also attended dozens of church recitals given by the choir my mum sings in (still). That introduced me, often very willingly to a wide range of secular and church music from the 16th century to the present. I completely agree it's a great way to get closer to some absolutely amazing music. There is an intimacy about such concerts that is rare in any venue (although you are sometimes at risk of coming out with a chilly numb bum).
If you're interested PM me for details of their next concert in St Alfege, Greenwich on 05/04/14. They are a small but very high quality choir and their concerts are always carefully programmed and superbly sung. This concert will also have a very good cellist, organist and guest soprano in attendance.
Read music reviews by all means and if you can get to a couple of major concerts then do. Don't worry where you sit. If you close your eyes and try to work out where the second bassoon is you may find you can't - fact of life I'm afraid. I was disgusted as a teenager to find the imaging in the Festival Hall was significantly worse than my relatively inexpensive stereo in my bedroom. Of course I had forgotten in my excitement for all things Linn how magnificent that full orchestra had sounded there (oh - that fantastic advertising, imagining you were a nude diamond(!) cannonballing down a mountain-sized record groove at the vinyl-equivalent to Mach 1 or some such BS)!
Get into the habit of listening to Radio 3 every week if you don't already - very little old-fartage apparent these days, you'll pick up tons of good stuff. There are often amazingly good concerts (last Thursday and Friday there were repeats of two whole Proms concerts played by the Oslo Philharmonic under Vasily Petrenko with great works by Beethoven, Bruckner, Tchaikovsky, Rachmaninov and Szymanowski. The sound was incredible. The playing was even better and made me sit up and listen. A very few obvious bum notes, but somehow it made the performance more real, more like you were there. A truly wonderful orchestra. Somewhat different but highly accessible is Late Junction, providing an exciting bridge between multiple genres (often way outside classical confines) and often has stunningly good sound quality on FM, just as the grid is nice and quiet. There's a good thread about how valuable R3 is in the classical section here at the moment.
Try also to get to a few local concerts a year, they are not usually expensive. Many will be in churches. Get to know the sound of the performers and perhaps hear them in other venues too. You'll soon gain an appreciation of acoustic space (as said previously, not always great but can sometimes be amazing). More importantly you'll find yourself quickly lost in the music. Relationships between the various musical parts are sometimes more easily heard in choirs and small ensembles, all of which will inform your developing ear. If you can hear things going on in live rock events you'll have no trouble hearing 'into' the music in a classical concert. I often find it harder to follow what's happing in a complex studio mix or live rock recording than a classical one - maybe it's what I know, or maybe I just need a Naim system and a cosy fold from which to appreciate all the detail.
Bonzo, when you say you want to understand the positioning and workings of the orchestra to appreciate Beethoven's Fifth, it makes me oddly happy to hear - I wanted exactly the same as a teenager even though I played in an orchestra. I couldn't hear much beyond the woodwind section around me and the feckin' timps behind. What I really enjoyed was to hear everything laid out in front, I suppose as the composer intended his audience to hear. My first hifi (an LP12, MF B200 amp, butt-ugly MF MC2 speakers and funny solid-core DNM speaker cable) allowed me to hear much more than I'd ever heard before. My system has improved over the years, as with so many others on this forum, but the extraordinary thing to me is that with experience, through listening, through concert going and through listening again, my priorities have shifted quite a bit and I obsess far less about the micro-details and 3D-tactility (although I certainly do like to 'see' a mental picture of the musicians and their space) and much more about what's going on in the music. Perhaps, ironically, the hifi, or rather the obsession I had with it as a boy and young man, has provided me the means to grasp music more fully, even though I do not class myself in any way as a musician. It's not an entirely unhealthy hobby, contrary to many people's belief!
Above all, forget about being an audiophile. Go to concerts to hear pieces, performers, things you haven't heard before. Often the group or choir will have recordings of theirs for sale at the interval. Have a glass of wine, spend a tenner, support the players (many groups are registered charities and operate on a shoestring). When you put the CD on at home they will reappear, making more sense; you'll quickly relate to the acoustic because you understand the size of the group and their sound (although it likely won't be the same venue in which you heard them perform). You'll have a connection to something you heard in recent memory and possibly really enjoyed. Even if you didn't you'll have engaged with it - god knows how much brittle, up-itself 20th century grunge I've suffered in the name of loving music (no, not the Seattle school). But in EVERY concert there has always been at least one thing I was glad I heard.
Your life will be richer for it. But keep rocking too...
All the best