Not unusual and may actually be a good omen to have to turn the volume way up before things actually "sound" loud.
What matters is can volume be turned up enough to satisfy and do dynamics continue to expand as well as the volume goes up. If dynamics start to compress and volume no longer increases as volume goes up, that is an indicator that
1)the amp is clipping which is never a good thing and should be avoided at all costs. How loud things can go is largely a function of speaker efficiency and amp power rating. Room size, acoustics and distance to speakers when listening also matter.
and/or
2) speakers are not designed to go loud and clear and enough are being over-driven by the amp. This is most often the case when smaller speakers using fewer smaller drivers are played loudly in a larger room. You need bigger speakers in bigger rooms in general in order to go loud, especially with extended bass.
In your case, the tube amp is probably up to the task of driving those little speakers but those are very low efficiency speakers that go for a lot of bass in a smaller package, meaning that they will require a lot of power to go loud, and also the size including only a single 5" woofer ain't gonna cut it very well in a large room unless extended flat low end bass doesn't matter for you.
Bottom line, speakers too small for the room. That tube amp probably does a decent job driving them, but they are inefficient speakers and getting a lot of volume may still be a challenge. Tube amp may be soft clipping and limiting dynamics plus speaker drivers may be being asked to work beyond their ability in a large room, not a good combo if so.
My advice, if your goal is to go loud and clear as possible in a larger room with the tube amp, would be look for a larger pair of more tube amp friendly higher efficiency speakers. Zu or Tekton might be a good place to start.
