First of all, set a realistic goal. You aren't going to turn your friends into audiophiles. (One or two might one day turn themselves into audiophiles, but encouragement/pressure from you will not do the trick.) Your goal should be to get them to better sound than they have now, whatever their budget is.
That means: No tubes. Tubes are for committed audiophiles, not for people whose friends want them to be audiophiles. Ditto any other non-current technology (except a turntable if they already own a bunch of vinyl). Keep it simple.
You say they already have an Onkyo receiver, and I'm sure they already have a DVD player. So speakers are the key here. How powerful is the Onkyo, and what speakers do they have right now? And what are they (or you, if it's a gift) willing to spend?
That means: No tubes. Tubes are for committed audiophiles, not for people whose friends want them to be audiophiles. Ditto any other non-current technology (except a turntable if they already own a bunch of vinyl). Keep it simple.
You say they already have an Onkyo receiver, and I'm sure they already have a DVD player. So speakers are the key here. How powerful is the Onkyo, and what speakers do they have right now? And what are they (or you, if it's a gift) willing to spend?