Yes, if there is a fixed line out on your Sophia (tape out), then you could connect a dedicated headphone amp to it. May not be the solution you want to hear, as your headphone listenting will not be benefiting from the glorious tubes.... but if this is a concern, there are various tube headphone amps out there for reasonable money, such as from Antique Sound Labs and Bottlehead.
I agree, puting a device in the signal path to your speakers is probably not a good idea, and a dedicated headphone amp is, IMHO, the best way to go for better sound.
I agree, puting a device in the signal path to your speakers is probably not a good idea, and a dedicated headphone amp is, IMHO, the best way to go for better sound.