Analog system, upgrade preamp

purchase most of my equipment during 79-82 timeframe while serving overseas.  Amp is SAE 2600.  Purchased Carver 4000 (used) to replace Carver CT-7.  Not happy with it.  Looking at Classe CP 50 or Conrad Johnson PV 10A update to the preamp.  have searched and do not understand how the "Balanced and Unbalanced" connection will fit into my system which all jacks are RCA.  Do now want to start a change and end up changing more than intended.  trying to bridge a nearly 40-year gap in my equipment however, the knowledge gap may be impossible.  Any advice on either of these two pieces and how they would fit into a completely ancient analog system would be greatly appreciated.
Balanced usually uses xlr connectors. Unbalanced, or SE (single ended) usuallt uses RCA. Don’t get hung up on it, just use rca to rca and you should be fine.
Well the good news, not much has changed in 50 years. You still need speakers, amp, source, and wire. The integrated amp is still the best performance and value, at least until and unless you get up into big money. Tubes, records, high sensitivity speakers, RCA not XLR- none of this has changed.

What has changed is everything now is so much better it is throwing good money after bad to try and keep what you have. Unless your budget is real tight you will do better to start new.

I would not recommend separates, not unless your budget is well into 6 figures. Probably the biggest change in 50 years is wire. Back then there was almost no difference, you could use dirt cheap wire. Today wire is so good it is a component in its own right, every bit as important as the speakers, amp and source. So budget accordingly. Which by the way, what are we talking about here, anyway?
Thanks for the prompt responses, had not set a budget but trying to probably stay under 10k for amp/preamp.  Recorded quite a bit back in the day that I recently started listening to again.  We use to swap vinyl so have a lot of cassettes. I  have Revox B77, Revox B215 cassette deck, (keeping), and some DBX equipment.  The speakers are La Scala and JBL 4312s.  Thought that the foundation would be the Amp/Preamp to upgrade to a softer less edgy sound. Did not know about wire upgrades,  still using old Monster wiring from over 30 years ago.  
Not going for surround sound tried a 5.1 and did not like the results. Hoping to upgrade amp/preamp and keep all old playback including Dual CS 721 with Shure V15V.

Paramount is I do not want to continue wasting time or money trying to figure out if a particular piece will do what I want.  Been at this for about 6 months now and not making any progress. 

Thought that the foundation would be the Amp/Preamp to upgrade to a softer less edgy sound. Did not know about wire upgrades, still using old Monster wiring from over 30 years ago.
Good to hear your speakers are nice and efficient. You do not need a lot of power, just good power. Short and sweet: Raven Blackhawk Do not be put off by the price, search the comments, read the reviews, this will sound a lot better than any separates you will find for under $10k.   

For speaker cables if you are under 10ft then it is definitely worth looking for quality. Lots of good used cables out there 6ft, 8ft length. Synergistic Research has made so many great cables over so many years you simply search and find whatever you can afford, do not worry, it will be so much better than Monster your jaw will drop. Then do the same for your interconnect. 

So you spent $4k on the amp, $2k on wire, and already I guarantee better sound than you can imagine. You keep the turntable, fine. Put it on a Townshend Pods Or a Platform. I use Pods under my turntable. But it depends on the situation. Your Dual might work better on a Platform. Either way, point is, these things isolate the turntable so well it improves the sound to a degree you will find hard to believe. 

This will probably leave you with just enough to upgrade your phono stage. Your Shure cartridge, if it is MM and 3.0mV like I think, then you can use the Decware ZP3 phono stage and you won't need a step up transformer.   

If you need to save some money the Nighthawk is $1k less and you can always buy cheaper wire. But the main thing to get across, with a Raven amp, Decware phono stage, and your turntable on Townshend, the rest of the stuff you have will sound so much better you will not believe.  

Check it out. Read the comments and reviews. These are all small companies that the only way they survive is by making really good stuff and selling direct to the customer. Very, very hard to beat. Certainly not without spending a lot more. 
Oh, forgot to mention, since you use tape- the Decware ZP3 has a neat feature where it can be used to replace the EQ on the tape deck. This does call for a simple mod to pull the signal directly off the tape heads and into the ZP3 via interconnects running directly between the heads and the phono stage. Read up, there is some info on their site. This one feature alone makes this totally the phono stage for you!
SIMPLY BLOWN AWAY!!! Thank you for every recommendation made i am starting my search immediately.  This is exactly what I needed was someone to lay it out for me because I've grown weary with research and trial and error. Forever grateful
Your Avatar is very very appropriate.  I have never owned an intergrated amp in over 40 years.  Did the research you suggested and called the company.  Spoke briefly with James, (one of the owners) and he continued my education.  Just purchased the NightHawk (color was the issue) and interconnecting cables and speaker wire as well.  Saving on their wires went to the NightHawk,  color choice.
 Synergistic Research had too many choices which made is somewhat confusing and Ebay had a ton of their products for sale which told me that many had done as i have in the past purchasing what you think you need and turns out otherwise.

Pods for the turntable are next and I am a bit confused with the  Decware ZP3.  It sounds like another tube amp from their site.  May ask for help as I try to understand it more.  Coming in under budget so far. 

Will update the thread once i get the NightHawk working. Do not have the appropriate words of gratitude for all your info. 
"Millie Grazie"

It has taken a bit of research and think I finally understand the ZP3.  all items have been purchased, just waiting now.

 I got my Night Hawk, and it is running as I write. The change was beyond expectations. I never thought that a small 20 WPC would be enough for the KLS or that my music was supposed to sound this great. I have put about 30 hours into it so far. Dave said it would take about 100 hours before I hear what it is truly capable of doing.  The volume knob has not passed one-third of the way yet. You don't need it!!  Still shaking my head in doubt and wondering what took me so long. My 12X22 room. I was a genuine SS diehard who has missed so many years of listening to music instead of hearing the sound of music. I hear the music now.
The NH is more than enough. I hear the music now as never before, and it beyond expectations. SoniQuil cables are more than adequate for my needs. I also added an Equi-Core 600 to ensure clean power without any potential interference. It Will be several months before the ZP3, and I can't wait.  
MC can't thank you enough. Truly grateful that you heard the desperation of my plea and responded. The improvements from changing two pieces have me evaluating the rest of my system now. I have the Townshend pods for my turntable however looking at replacing it as well at this point. LSA T-2 or EAT Prelude. These are within what I want to spend.  
MC, just one more opinion, please Found only one review on the Tekton Studio Monitors. I am replacing the JBL 4312. Their size would be a perfect fit where I want to place them.  
My wife is now a widow, and I am a widower. She has her thousand books, and I have as much music to catch up on.

"No one can tell me that I'm doing wrong today" James Taylor