Amplifier recommendations for 86 dB Sensitivity Speakers

@onhwy61 I agree, however for me its really about how it can sound even better and thus be enjoyed more too. Put another way its about getting the most out of your hifi investment. 

Just because a loudspeaker will work better with a big solid state amplifier doesn't mean it won't work very well with your moderate power tube amp.  I am not familiar with either the loudspeaker you are considering or your current amplifier.  The Technics isn't an easy load, but it's also not difficult load.  It's honestly rated at 4 ohms.  With 4 KT88s per channel your amp should have enough to drive them.  Depending on how loud you listen, your room and your musical taste you could find the Technics/Cayin combo absolutely fabulous.

@onhwy61 The speakers in question are only 83dB 1 Watt/1 meter. Sensitivity-wise this works out to 86dB, but we're talking about a tube amp here and they don't double power as impedance is halved. Instead they cut power in half as impedance is doubled if they are acting as a Voltage source. 

So this is simply impractical and won't work out as you forecast above. 

@mamifero If you like your amp, I'd look for a speaker that is 8 Ohms or more. Your current speakers are 4 Ohms so their actual efficiency is 87dB. Your amp is working hard all the time with that speaker- they are not showing it in its best light. By simply moving to an 8 Ohm speaker that is 90dB your amp will need only make half the power it does now for a given sound pressure level. That will reduce its distortion and it will run cooler as the output section will be more efficient. 

@mamifero I forgot some things. 

There is a phenomena known as 'thermal compression' in loudspeakers. Its where the voice coil heats up with bursts of power through it. The more it heats up the more compression.

This is why you read about more efficient speakers being more dynamic- with less efficiency (or sensitivity) the bigger this problem is. Vented pole pieces and the like certainly help, but do not solve that problem.

Here is advice I give to anyone who owns a tube amplifier:

If you want the most performance out of your tube amplifier investment, consider a loudspeaker that is 8 Ohms or more and as efficient as you can get (watch out for speakers with dual woofers which might be 4 Ohm in the bass but 8 in the mids and highs, which might simply be rated as 8 Ohms or '8 Ohm compatible'). 

All amplifiers regardless of technology make more distortion into 4 Ohms and speaker cables become far more critical too. Quite literally if you could make the speaker be 8 Ohms or more it would sound smoother and more detailed due to the reduction in distortion from the amp. This is especially true of tube amps. 

@mamifero The speakers you have in mind are 86dB and 4 Ohms.

Sometimes its worth considering what this looks like in terms of efficiency rather than sensitivity, since efficiency is stated in Watts rather than Voltage. This is especially important if you have a tube amplifier!

To convert from sensitivity (2.83 Volts/1 meter) to Watts you need to know the impedance of the speaker, which is 4 Ohms. 2.83 Volts is 1 Watt if the load is 8 Ohms (into 8 Ohms sensitivity and efficiency are the same thing), which means into four Ohms its 2 Watts. That's a 3dB difference, which to the ear isn't much but it represents a doubling of amplifier power. Tube amps don't double power when you cut the load impedance in half. 

Another way of looking at that is subtract that 3dB from the sensitivity spec; you arrive at 83dB. 

That is so inefficient that you may have real problems finding a musical sounding amplifier that also has enough power to drive that speaker much past a conversational level. In most rooms this means you'll want something north of 1000 Watts per channel.

If this seems hyperbolic on my part, consider that to double the apparent volume requires an increase of amplifier power by a factor of 10.

@dekay makes a good point! 

Since your amp doesn't double power into 4 Ohms this is a very practical concern. If I were you I'd consider a more efficient speaker as this combination will have the amplifier struggling all the time. If no-one has pointed this out yet, tube amps are less efficient using the 4 Ohm tap and tend to have less bass bandwidth (as well as slightly less power).

IOW I think that speaker with your amp isn't a good idea.