hi, I have been researching various "vintage" amps to help me decide on a purchase and have seen many useful bits of info from this site. I have always liked Sansui products from the 70's but have next to no idea on the differences between models. I am a total novice, but eager to learn at 47! I've been looking at Sansui 331, 551. Is it worth spending more on a more powerful model? Any advice greatly appreciated. I'm on crutches at the moment and have plenty of time to learn. Thank you to all , look forward to leaning more from this community. Dave from Melbourne.