Tardcore

assuming you are referring to the PM5004?  Amazon used to sell them via Warehouse Deals for less than $200 but they seem to have adjusted that price lately.  You can set up a camelcamelcamel price notification if you want to go that route or just watch Amazon prices.   Marantz has recently released updated models for the PM600x and PM800x series, you might see a new PM500x model soon which should drop the price.

upgrade that tree branch while you're at it.  it's killing your sound.

all of this is really to just avoid the inevitable "hey guys I bought this turntable for $50.  it came highly recommended here but it doesn't seem to blah blah blah.  help me fix it." thread.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

Personally, I would go the opposite route.
 
my main concern with closed back versus open back headphones in a work environment is sound leakage. my neighbors probably don't want to listen to whatever I'm playing.
 
And then on the other hand, I like open back headphones when I am out and about because I like to be able to hear a little bit of what's going on around me so I don't die or whatever when crossing the street.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

rules of the internet:
 
do not sell items on ebay to overseas buyers unless you are willing to lose said item and receive no $$$ in return.

To be clear, you have to use a pre-amp in one form or another (you should probably actually read this - http://lmgtfy.com/?q... a phono preamp)
 
The signal coming from a turn table is weaker than the signal that typically comes from another source like a CD player.  The phono pre-amp changes that signal into something usable.
 
Some receivers or integrated amplifiers have a 'phono' input with an on board pre-amp section.  You can bypass this by simply not using the phono input.
 
some (typically lower-end) turn tables have a built in pre-amp.  you typically have the option to turn this on or off as needed.
 
if a pre-amp is not included in either the turn table or the receiver/integrated amplifer, then you would have to get a seperate external phono pre-amp.
 
Based on what you said in your original post, it sounds like you have 2 pre-amps available now.   You can go ahead and add an external into the mix, but just be sure that no more than ONE is active at any given time.  Otherwise you are simply amplifying an already amplified signal.

OP said specifically that they were not looking for ear buds or in-ears....
 
I like my ATH-M50s well enough. can be had pretty regularly for $100 (monitor slickdeals.net for deals). 
 
they sound good and I wear them for ~4 hours every night.  However, they do get sort of hot after a while due to the closed-back design. 
 
Given that I use them exclusively at home, I may be switching to an open-back design in the future.  However, since you intend to use yours at work, you'll get better isolation from closed-back cans.

you can try it both ways.  
 
Either run your turntable into the amp's phono input without the table's onboard pre-amp engaged OR run it into any other stereo input with the onboard pre-amp engaged.
 
just don't run a phono preamp into another phono preamp.
 
additionally, the cable is short because shorter is better.  you do not want to run a weak signal from the TT over a long cable length.   If you choose to introduce an additional phono preamp into the mix...keep the line between the TT and the pre-amp as short as possible.

OP said specifically that they were not looking for ear buds or in-ears....
 
I like my ATH-M50s well enough. can be had pretty regularly for $100 (monitor slickdeals.net for deals). 
 
they sound good and I wear them for ~4 hours every night.  However, they do get sort of hot after a while due to the closed-back design. 
 
Given that I use them exclusively at home, I may be switching to an open-back design in the future.  However, since you intend to use yours at work, you'll get better isolation from closed-back cans.

I like my Emotiva XDA-2 ($270) or as pointed out above, you can get the Marantz PM6005 ($700).   Most of the recommended 'entry level' options fall in to the $300ish range (Cambridge Audio Dacmagic ($300), Schiit Bifrost ($360 and up).  
 
Price difference being basically a wash, I tend to prefer having a separate component, but others may prefer the integrated option.
 
If you're looking for a cheap cheap cheap solution, I just bought a FIIO D3 ($30) to use in a bedroom system (PM5004 + Apple TV) and it works well enough that I will likely keep it around until I upgrade my living room DAC at some point and move the XDA-2 to the bedroom.
 
I guess it is also worth mentioning that the PM6004 is mostly hard to beat because of its clearance price.  I'm sure there are other integrated amps with DACs to consider in the $700 range.

upgrade that tree branch while you're at it.  it's killing your sound.

I like my Emotiva XDA-2 ($270) or as pointed out above, you can get the Marantz PM6005 ($700).   Most of the recommended 'entry level' options fall in to the $300ish range (Cambridge Audio Dacmagic ($300), Schiit Bifrost ($360 and up).  
 
Price difference being basically a wash, I tend to prefer having a separate component, but others may prefer the integrated option.
 
If you're looking for a cheap cheap cheap solution, I just bought a FIIO D3 ($30) to use in a bedroom system (PM5004 + Apple TV) and it works well enough that I will likely keep it around until I upgrade my living room DAC at some point and move the XDA-2 to the bedroom.
 
I guess it is also worth mentioning that the PM6004 is mostly hard to beat because of its clearance price.  I'm sure there are other integrated amps with DACs to consider in the $700 range.

I just pour draino on mine.

I just pour draino on mine.

I just pour draino on mine.

I support anything that isn't plugging a phono preamp into powered computer monitor speakers.

just get 6 pairs of powered studio monitors and chain them all together.  wall of sound, bro.

you should probably rethink the whole trying to get an 'advance' notion. 
 
turning in a piece of paper that says you completed work that you did not actually do sounds a lot like academic fraud.

still trying to figure out you cannot come up with 15 hours over the course of nearly a week to pick up some cans in the park or something.  online classes must be rough.