Impedance mismatch

[sussexhalf]

This is pretty basic stuff for those of you who know their Ohm's Law or who have a history of driving different amps through different cabs.
I want to connect a Matamp Minimat valve 2 watt amp to a Celestion Alnico Blue 12" 15 watt 15 ohm speaker. The amp's output is quoted as being 8 or 16 ohms.
What are the issues around the 1 ohm mismatch?
I'm not worried about losing volume, but I am concerned about the effects on tone, and / or damaging the amp or speaker.
I'm aware that I should use proper speaker wire, not an instrument lead, btw.
Thanks guys.

[SatelliteAmps]

There is no difference. 15 or 16 ohms is essentially the same thing for all intents.

[sussexhalf]

Thanks Adam, I kind of thought that that might be the case, and you've removed my worries. There's not much difference if any in the cost of Celestion Alnico Blues in differing wattages and impedances, but I've found one as described on eBay, brand new in box, for a lot less than retail.
Thank you for your response.