Will a high quality preamp really make a difference in sound?? Also speaker cable

Clearly you should seek out the best engineering and scientific perspectives on this question which means you should choose a pre-amp that delivers exceptional measureable performance. There are so many exceptional performers out there. You can consult resources like Audio Science Review to learn more about amplification and audible thresholds. There are also useful notes on source switching noise and power-on behavior.

Professional engineering and science has not found much value in high cost cables, alas, but very high quality pre-amps for reasonable prices are quite easily obtainable.

Your system is only as good as your weakest link.  This doesn’t mean you have to spend gobs of money.  It means you spend on quality gear that gives you your desired sound.  

I think I would reframe the question.  Is a standalone preamp with lots of inputs necessary?  If you only listen only to digital then many DACs have well implemented preamps built into the unit (not in digital domaine).  If you listen to digital and vinyl as I do, some DACs have an extra analog input as does my MSB Reference. 

Preamp: duh.

Cables: The Cable Choir may have made a Religious Convert out of me!

The other day, I put in a different cable that was a foot longer to run from my phase aligners to my amps. Afterwards, something didn’t sound right. I switched back. Better!

I have no idea what the brands are. The longer one was sheathed in a synthetic fabric. The other, in rubber.