Yes and No.
Yes as in you can use X7s as a pre-amp to SP200 without causing any fire/explosion.
No as in you might not be getting any of the 'Class A sound' from X7s. Class A means the amp section is running in Class A mode, but given you are using it as a pre-amp, where the analog music signal should be in Pre ( = before) Amp (= amplification) condition thus should not be processed by the Class A amp section. Using as a pre-amp, X7s should only act as a volume knob and not do any amplification to the signal. You will get the Class A sound if you double amp, but that most likely going to degrade SQ. If you don't double amp but only use X7s as pre-amp, you are kinda wasting your time since SP200 already has a perfectly fine volume knob.
Given what has been said, there is no harm in trying since you already own both. If X7s somehow has a zero gain buffer stage that does go through the Class A amp section, then maybe you will get the Class A sound at the end.