Amp vs Preamp which is more important?

In my opinion, the pre-amp first.  I would get the best pre-amp I could afford and build from there.

The Amp also depends on speakers selected.  So there is a back and forth involved.

Hi efficient speakers don't need arc welder style amplification.  Or, not so efficient speakers need more powerful amplification or if the speaker's impedance is low, then you need specific amplification to drive them correctly.

But, the pre-amp is typically not system dependent.

Also, yes, there are digital sources that have volume controls incorporated.  However, they typically are not internal pre-amps and therefore are not control amps that have multiple inputs.  So if you decide to have more than one input source, that digital source with a volume control really doesn't cut it.

You have an SP16 pre-amp.  That pre-amp has a decent incorporated phono section.  So, you currently have multiple inputs, volume control and a decent phono section.

My recommendation is to "borrow" a REF 3, REF 5SE, REF 6.  Take them home, and listen in your system doing an A/B comparison with your SP16.

I did that with my SP9 MKII, SP11, REF 3, REF 5 and REF 6. If it wasn't for wanting remote control capability, the SP11 is outstanding.

However, the REF 3 is very nice indeed, even compared to new pre-amps.  You can't go wrong with a REF 3.  The REF 5 vs the REF 3 didn't show enough of a difference to warrant (justify?) upgrading to the REF 5.  Just not that much of a sonic improvement.

however, the REF 6 vs the REF 3 was a noticeable difference.  Then I got a deal for a REF 10 (the best) that I could not pass up.

looking at your current system, The only thing i would consider upgrading at this time would be the pre-amp.  Go for a REF 3 or a REF 6.

enjoy

As a Tube guy, I like integrated.  Not sure that is the same in SS since there are less good integrated choices.  but a good integration ensures harmony.

Jerry

The sound signal is your car and pre amplifier and amplifier are two part of highway. We will experience traffic problems when  lane numbers shrinked, that happens with the signal. It could be that the pre is more important, it could be that the amplifier is more important depending how good the other one. General speaking, the weak one decide.

Once my system was no longer entry level and I was at the point in which the speakers I owned I considered my final pair I started what I called the final upgrade circle. I then upgraded the piece of equipment that was lowest in both cost and where they sat in that brands line. Yes cost can be a determiner. The higher you move the more you must spend to hear significant jumps. Eventually you begin to hit your maximum dollar amount you will want to spend on individual components and this starts that last circle that will level them all so hopefully one component does not hold your system back. The most interesting were the amplifier and preamplifier upgrades, My last two components that needed to be upgraded. These upgrades was where I realized how incredibly important those two components were. They really brought the sound to a level I never thought I would have been able to obtain

With all the above said some one mention the preamplifier partially due to its difference in cost to the amplifier. I agree with that analysis and it was proved to me when I went out on a limb and purchase my first to me really expensive preamplifier that was significantly more expensive than my amplifiers and heard what a difference it made. I believe if you are near the end of your upgrading purchase go for the preamplifier before the amplifier.

The only thing at this point that will be upgraded will be my DAC and streamer and only due to some unknown changes in music delivery and technology changes in those areas. This is not to say I have the best system around but I hit my limit in what I can spend and am very satisfied with the system’s sound. Took years like most people.

I am no audiophile by any stretch with the gear you guys are used to, but I have a new friend that is... He sold me a pair of Zu Dirty Weekend speakers he bought new in 2018. When I went to audition these speakers at his house, I was amazed at the gear he had laying around and or in boxes. His one listening area he had a pair of $12000 speakers, Tyler Acoustic Woodmere II's that Tyler built special for my friend, and delivered personally back in the day. He had a $10,000+ tube amp just sitting on a furniture dolly, various other amplifiers on furniture dollies, and gear from manufactures I have never heard of. 

He has three systems, and get this, he is running PS Audio Stellar Gaincell preamps in all three, along with the Parasound A23+ amplifiers. No external DACs, he uses the one in the Gaincell. 

I bought the Zu speakers from him, brought them home and hooked them up to my system, Denafrips Venus II 12th DAC, their Athena Pre, Thallo amp and I had two Emotiva XPA-2 amps, one original and one DR2. It sounded like crap with the Zu's... Currently own the KLH Model 5's. 

I talked to my buddy, he has owned all of that same Denafrips gear, has Alvin's cell number. He sold them all. Go get yourself a Gaincell and A23+ kid... And that is what I did. 

I found a used Gaincell, and purchased a new Parasound A23+ and cannot believe how these two pieces work together, even the DAC in the Gaincell bested my Venus and Athena. Four sets of ears agreed when we did an amp/speaker shootout here at the house. The A23+ and Gaincell won hands down with the Zu's. I have the same amount of money invested in this system now as I do that one Venus DAC.

What is my point? I don't know, but my new buddy with tens of thousands of dollars in gear laying around his house decided that this is what sounded the best to his ears. He jokes about it when looking around at all of the gear he has just sitting there, that this is the system that does it for him. A discontinued entry level preamp and an inexpensive more or less consumer amplifier. Who would have thunk?