Hi i have platinum audio bookshelf monitors that do not sound right...

OP
I think he needs go for 10 years minimum for sure!
I understand your thoughts and certainly give the Krell a try, just I have found over the years some items when gains do not match up perfectly I have had the volume up too (80% on one combo I remember) and as it sounded ok to my ears I did not lose too much sleep over it.
Let us know how the Krell works out, I can always give it a home if you are really struggling....lol

Uberwaltz
Hi and thanks for your response, i understand what you are saying, but i don't think i should have to turn it up so high just to get a satifysing sound, that's why i'm gonna try a higher power amp, As for my rich friend, its his son's Krell, while he's  away at college (i'm gonna try to talk him into going for his PHd, i' know i'm gonna hate to give the krell back.  Will up date at a later time....

What is it with all these people around here who happen to have rich friends who can toss them a Krell they have lying around or a set of Nordost Valhallas they do not use.
I must be moving in the wrong circles methinks!
Luck to be given a 3 day old half eaten cheeseburger!

Seriously those Platinums just need some more current to kick into high gear.
One thing you did not mention though, even though you say you need 3/4 preamp volume to get the output you desire what does it actually SOUND like at that?
I mean if you like it, the amp is not clipping etc then there may just not be an issue at all. Or not an issue that requires fixing at this time.

My dealer used to sell Platinum Audio. W/the Solo's you needed a minimum of 200 wpm for them to sing. Heard them demoed way back w/a pair of Parasound JC-1 mono's.  Big sound w/plenty of bass. Designer Phil Jones is big on bass. One reason his Solos were 84db.

Thank you all for the responses, i am gonna go with another amp, i have a rich friend that has a Krell he is not using and see how that plays out
                                   Most Regards,
                                       Jeff.....

I read JA’s review of the Solo’s for Stereophile. Those speakers are rated at 84db @ 6 ohms with a 5 ohm floor. The Cary SET amp JA tested was struggling to drive the Solo’s, and his conclusion was they "need a lot of amplifier watts to come alive". Your McIntosh amp is outputting approximately 125 watts @ 6 ohms with a damping factor around 150. Those are modest specs, and suggest your amp is on the low side power-wise.

Mcreyn is right, according to the amp’s Owner’s manual, your amp has adjustable gain. So if the gain switch is set to low, it’s worth experimenting with a higher setting. That said, I had a similar problem when I was driving my old Marten Coltrane Alto’s (87db @6 ohms) with a Classe Cap-2100 integrated amp. The Classe was outputting around 150 watts @ 6 ohms, but struggled to drive the Alto’s which need a lot of power. In that setup I was running the Classe pre-out to my Ayon CD-5 (as linestage). Ironically I initially set the Ayon’s gain selector to ’high’ (8v) which tripped the Classe’s protection circuitry. I had to back it off to the low setting (6v) to resolve that issue. Yet even with that (still high) gain setting, the Classe struggled. It wasn’t until I upgraded to a Boulder 1060 power amp that the Alto’s came to life. For the first time I was hearing (and feeling) deep bass, and they sounded effortless.

My hunch is your McIntosh power amp is under-powered for your speakers. I can understand it if you have a sentimental attachment to your vintage McIntosh gear, so you have two options. You could sell your Monitor Audio speakers & buy some more efficient stand mounts, or you could buy a more powerful amp. I’m personally a fan of integrated amps. You can find some very good integrateds on a limited budget. Lately there has been a bit of hooplah on ’Gon about the Hegel H360 which you can pick up in good shape 2nd hand in the low $3k range - https://www.audiogon.com/listings/lis91cg7-hegel-h360-solid-state I also saw a mint/new Hegel H190 on the ’Gon asking around $2.9k. Those amps have a very high damping factor, so they would have no problem driving your speakers. They also include a dac & streamer. Hope that helps.

Having to turn it 3/4 of the way is not an issue, it just means there is not as much gain than some other combos (your amp has adjustable gain).  Are the power guard lights on the amplifier coming on, which would signify clipping?   That amp should have enough power to cause the woofers in those speakers to bottom.   

If I were looking at an upgrade, I would be looking at the preamp, but from what you are saying, there is no issue, and no reason to upgrade unless you want to.  

The room is rather small, (14' X 12') 12 foot ceilings, listen to all types of music (not tooo much rap please), at moderate levels. I do however have to turn the volume up over 3/4 to get a punch !!!

They might also need work on their crossover. I only say that because they're getting a little old now, and it's hard to imagine that a 7100 isn't enough to drive those speakers. 

What don’t you like with your current setup?   How large is your room?  What do you listen to?  How loud? 

Wires (Cardas) are correct.
Model name "SOLO"

To better assist you, can you specify which model Platinum Audio monitors you have?