Is my ceiling too low?


Hi, I am going to move to a new house with a 15'3"x12'x7'8" (LxWxH) room in the basement as my future dedicated listening room. Is the ceiling too low? I am listening to a pair of Harbeth HL5 with Naims.
I am a little bit upset because I had a chance to ask the builder to make the basement ceiling higher such as 9' but I didn't because I thought the ceiling would be 8ft, which I think it's ok, until recently I double checked my blue print: it's 7'9" minus the ceiling and berber carpet, not 8ft...and it's too late the change it now...

Please give me some opions, thanks!
hififish
I had a room with low ceilings with reynaud offrandes, one of the best sounds I have experienced. As I remember the tweeter is below the driver on that model which may have something to do with the results.
Do you bump your head?

In all seriousness, I have a soffit for the central heating/cooling system ducts that is 5' wide and runs the width of my room directly over the sweet spot. It reduces the ceiling height to 7'4' in this area. This has never presented an acoustic problem in the 20'x 28' basement room.
Sure, the higher ceiling would be better but the Harbeth's are not very room sensitive and you will get some really great sound pairing them with the Naim stuff--provided it is the NAP200 or better. Enjoy!
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Thank you so much for all the helps! Now I know there are still many things that I can do to get a great sound in this low-ceiling room. I think the first thing I would do is to ask my builder where the duct will be in this room and how wide and deep it is. Now I have another question, if you have a choice, where do you want to have the duct in a room like mine, close to your speakers or close to your chair? Thanks!