Hi, can you tell us what you are using as a source? For audiophile quality sound the source is a very important aspect. If your source is going to be a generic consumer CD player, I would honestly recommend that you keep a bit of that 50k aside for getting a good CDP as well.
Generally the speakers are the most important part of the setup, so I'll start from there. Disclaimer, i am not an audiophile, just an audio enthusiast, so these are just some pointers before the people who know their stuff can advise you better.
Speakers
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There are two options for you here, going for (moderately) high quality bookshelves or medium quality floorstanders. (moderately) high quality bookshelves start at about 10k, and these include the Wharfedale Diamond 9.1s (11k), Polk Audio RTi A1 (14k), etc.,
Or for a slightly higher price you could go for lesser quality floorstanders like the Jamo 406 (a pair should be what 16k?...wait futurebazaar has the whole 5 speakers package for 17k) or the Polk Audio Monitor 50s (19k). These will probably have slightly inferior detail and clarity but will provide better bass thump which you may want for rock music.
Amplifier and CDP
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Depending on how much you spend on your speakers, you can have anything between 38k to 30k left for the amp and CDP. If for instance you go for Wharfedale 9.1s for 11k....you'll have 39k left, then you could consider going for a combination of a Cambridge Audio 340C CD player (14k) and a CA 540A (20k?) or a CA 640A (25k?) amplifier.....if you've spent a bit more on the speakers, you could consider economising on the source and going for a Cambridge Audio DVD89 which is a 1080i upscaling DVD player that also does a good job of playing audio CDs....this is for 10k......
there are other options from marantz and NAD as well in these price ranges, which others I am sure will chip in with.
At the end of the day listen to all these things....spend all the time that you can afford to spend....and see what makes you happy.