Just my personal opinion and experience, the zen, scm40 and shl5 are too big for your room.
Since you are using tube amps, if they are less than 100w, the scm40 is out of the pix. these speakers need a lot of s/s power.
for your room, its probably better you go with the harbeth c7es3 or the P3esrs.
if you go to the atc route which are also very good speakers, the scm11 would be a better choice but you'd probably have to upgrade your amps.
good luck.
Since you are using tube amps, if they are less than 100w, the scm40 is out of the pix. these speakers need a lot of s/s power.
for your room, its probably better you go with the harbeth c7es3 or the P3esrs.
if you go to the atc route which are also very good speakers, the scm11 would be a better choice but you'd probably have to upgrade your amps.
good luck.