Will 2 watts monoblock 45 tube amp work for 90db speakers ?

think I would be looking for speakers in the 94-98 db eff range for use with a 45 SET amp....they are really about 1.5 watts, 2 watts is pushing them pretty hard.

Actually 1.5 watts is about double what you traditionally get out of a 45.  You really do need speakers that are more efficient. I ran some old full range speakers that were rated 99dB with my 45 SETs in my bedroom- and that was volume challenged- they sounded loud not because they were but simply due to those higher ordered harmonics I mentioned earlier. The ear uses those to sense sound pressure, so when the amp makes them it sounds louder than it really is. The problem is, it doesn't sound as nice when it does that.

@cal3713 thank for your info , this is very handy tool to have 

And if you don't have a DMM, they're worth having around... I bought this one for $25 and it does just fine.

https://www.amazon.com/Alloet-True-RMS-Digital-Multimeter-Voltage/dp/B072JMBLJS/ref=asc_df_B072JMBLJ...

If you have a multi meter, you can use the test tone & technique provided here to calculate how many watts your speakers actually use: https://www.diyaudio.com/forums/multi-way/204857-test-voltage-power-speakers.html

It’s super informative & useful: all you do is set your volume at the max listening level you use, then play the -12db 120hz test tone while measuring voltage at the speaker terminals. Square that value and you’ve got the maximum watts needed. Plenty to read at the link...

think I would be looking for speakers in the 94-98 db eff range for use with a 45 SET amp....they are really about 1.5 watts, 2 watts is pushing them pretty hard.

@atmasphere good info 

@soix thank for your suggestions but I think I have a wonderful combo tube  preamp plus tube dac feed to my lovely Yamaha mx1 with dual transformer , the mx1 I purchased was 600 bucks compare to 2500 as new and I think I got a very nice combo already , for now I just want to try low power tube amp with high efficiency speaker for low volume listening 

I've heard Ralph from Atmasphere say that you don't want to push tube amps to the higher end of their output range as their sound quality begins to suffer, so you may want to consider that as you search for an appropriate tube amp.

To clarify this- the statement above is true of all amps, but in the case of SETs the higher ordered harmonic distortions start to show up at about 20% of full power, so if you really want to hear what the amp does you need a speaker that allows you to run the SET with all forms of music at power levels less than 20%... in the case of a type 45 based SET, that means a speaker that is about 105dB or so at a minimum in most rooms.

Here's another option you might consider that should have no problem driving your speakers.  Not tubes, but SS Class A that does a nice job blending virtues of both tubes and SS.  Read the reviews. 

https://www.usaudiomart.com/details/649533832-valvet-e2-amplifier/

I've heard Ralph from Atmasphere say that you don't want to push tube amps to the higher end of their output range as their sound quality begins to suffer, so you may want to consider that as you search for an appropriate tube amp. 

Best of luck in your search. 

90db speaker is not efficient enough.  I would be looking at speaker with an efficiency above 98dB.  

@rocray do you run subs along with them ?  

I disagree! A SET 45 amp is good for 1.75 watts. Enough for any headphone. I have one made by Will Vincent. I also have a pair of Heresy Mk I's  that work well with it. So high-sensitivity speakers are the best choice.

Most you can expect is to use them for headphone amplifiers. Even then they’re a little wimpy. 

I occasionally run my Boxer 2's with a 10 watt tube amp. It works fine at lower to medium listening levels. You will not have to worry about the neighbors calling the police. 
    Hope this helps,
       Ray

Thank guys ! I may have to go for another pairs with higher watts than 2watts , maybe 10 watts class a will enough for my listening level , normal I don’t listen more than 9 o’clock on my 100 watts ss power amp. 

Not enough power amps will clip and give you NO bass or dynamics.If you want to use amps of this wattage you need 98db efficient speakers or you will be in clip city.Enjoy!!

Will 93 dB satisfy you? Because that is what you will get at 2 watts.

It won’t satisfy you for long.  Not only will a 2w amp not have enough power for loud levels with a 90db speaker, it also won’t have enough control at low volumes.