Tell him/her that you're looking primarily for a jazz tone - FYI there are subtle tricks (
very subtle, and none of which are DIY in nature) that can be played with bias current - here's a bit of background:
https://valvetubeguitaramps.com/the-...ting-the-bias/
I assume you already know that the Preferred Series EL84's come with a numerical rating (the higher the number, the higher the potential headroom and the slower the breakup); since the Monoprice is sold as a "rock" amp (which BTW allows the manufacturer to use weaker/lower-quality tubes, for quicker power-tube breakup - not to mention lower production costs
) those Russian mil-spec tone bottles will likely need a bit of massaging (definitely a bias adjustment, possibly replacement of a couple of components to allow fine-tuning) to get the tone you're after. Not to worry - FYI this is not an uncommon procedure for tube amps - and when you're done you should have a lightweight little tone box that'll be an old-school complement to your Eastman...
