Best Sounding Adapter - Making RCA into Banana or Spade? Thanks!

In my car stereo days, we referred to these genercially as "high-to-low-level adapters".  Speaker level in.  Line level out.  Depending on your level of persnicketiness, you can find these at a variety of price ranges.

Another consideration here is that you have a single RCA cable and your amp has left AND right channels.  While bass is generally summed to both channels, you can take your pick of left OR right. You may want to look for a "summing" adapter if you want to make sure you capture all the bass information.  Probably overthinking this a bit, but just throwing it out there IF it matters to you.

As far as termination on the amp end is concerned, it may depend on you amp.  IF your amp has speaker A and B connections, then connecting to speaker B will give you a wide range of connection options.  IF your amp has speaker A only, then. you will be joining other speaker connections which may make the connections more challenging.  If you are using bananas, for example, adding more bananas is certainly above my pay grade.  But, generally, raw wire is best, but takes a little more time a patience to get it right.

Thank you to everyone who has kindly shared their thoughts - much appreciated!
I’m certainly learning and appreciate the insights and caution too. My rig is:

Integrated Amp - Unison Research "Unico" (Gen. 1 with the IR remote).
It has speaker outputs and a "Tape" RCA output.

Home Theater / Audio Tower Speakers - Definitive Technology BP2000.
Bipolar, so same speakers back and front, plus a 13" 300W sub-woofer.
Each tower has three pairs of binding posts - ’Low,’ ’Medium’ and ’High.’
The ’Low’ / sub woofer also has the RCA input option.

Currently I use one set of speaker cables from the integrated amp to the ’Middle’ binding posts of each speaker. Then jumper cables from the ’Middle’ to the ’Low’ and ’High.’

Q1. Can the "Tape" RCA output connect directly to the sub-woofer RCA input?

Q2. If "Yes" to Q1, is this typically better sounding than the jumper cable set up?

Q3. Does bi-wiring or tri-wiring speakers sound better than all the above?

Thank you in advance for your thoughts! :-)

If I accurately understand your question, you wish to connect an RCA (line level) to permit use of speakers terminated with banana plugs. May I suggest using a Fosi Audio TB10D? I purchased the unit on Amazon for under $70. It is a simple mini power amp equipped with volume, treble, bass control, and a 32V/5A power supply. I have a JVC VHS/DVD player and  inserted the RCA connectors and speaker banana plugs into the TB10D to power a set of 4 ohm MartinLogan towers.       

@vinylfun 

Let me take a shot at your questions:

Q1: the tape out is a fixed output, meaning that it does not change with volume.  Yes, it could connect to your sub, but it would be rather tedious to adjust the volume on the sub each time you adjusted the volume on the amp.

Q2: answered with Q1?

Q3: This group is all over the place on the subject of bi-wiring.

Looks like we're circling back to a high quality high-> low adapter?