I have had various speakers and amps. Almost all amps I have had were tube of various wattages and speakers that varied from 86 db to 90db, 4 ohms, 8 ohms....you name it.
Frankly in my modest sized rooms and listening to levels in the 85-90b range, I rarely found I lacked power. I might have found that were I to have used a 20 watt amp with the 86db speakers I would have had an issue but I would never have done such a mismatch. But 100 watts per channel is lots of tube power. That being said, some speakers do work better with lots of power and then you probably would want a beefy solid state amp.
I completely agree with posters suggesting you are dealing with issues where there is not enough voltage coming from your source to drive your amp properly. You claim that you have much more output with your CD player and less with your phono preamp.
Most CD players have a healthy output of about 2 Volts and most amps input sensitivities are such that they will deliver full output with about 2V input so you have likely a good match between your amp and CD player.
The issue, I think exists within your phono preamp and cartridge. Most phono preamps have a fixed gain. They will put out a healthy voltage output if the phono cartridge has enough output. However, cartridge outputs vary a lot.
For example, If your phono stage needs a cartridge that puts out 2 Millivolts for a full output into your amp, and the cartridge you have only puts out 1 Millivolt, then that is your problem.
Perhaps you could post what cartridge and phono preamp you are using? I suspect that once you have that sorted out, you will find that the amp you have will be sufficient to drive those 86db speakers rather well. I think a change in your cartridge to one of higher output or a change in your phono preamp to one with more gain (some phono preamps have variable gain switches and are adjustable in fact) will probably improve the phono side of things irrespective of what you do at the speaker end of things
Many in this hobby, piece their systems together, buying from various sources online. What that approach lacks, if you don’t have the experience, is the knowledge and expertise gained from a brick and mortar dealer who would guide you through the process to ensure component work well together. I am not a dealer, but knowledge and experience goes a long way towards helping avoid these mistakes. Forums are useful, but as you know, everyone has an opinion, and many times they are wrong.