I have used Cabasse speakers (Caravelle, Farella, M2) with tube amps with excellent results. All are around 93.5 dB 1w/1M and work well with the SE and PP tube amps I own. Cabasse speakers are hard to find used. The most I paid was $850 for the used Farella's in perfect condition. Caravelle's were designed specifically for tube amps and are an easy load to the amps. How much power are you planning to use? How big is your room? How much do you want to spend on the pair of speakers? There are a number of choices so if you include those details, perhaps some of us can help you with additional suggestions.
Brad
Brad