not seeing your set up but by your description it sounds like that would roar. without a barometric you have no means for contolling draft. you have an air inlet and that is for suppling air for combustion. you could probably control your draft somewhat but then you fire would always be changing in the process. if you have a means and room for adding a baro i would do so.
what a barometric damper does is to keep a constant draft on the stove with out changing the fire and letting it burn away which a by product of that is a lot of heat being drawn outside when it is needed inside. when you light a fire draft is created. as the fire intensifies more draft is created, at a certain burn rate more draft is created than what is needed. at this point the baro will sart to open and maintain whatever you have it set at. (i set mine at-.05)
when the baro opens it keeps an -.05 draft on the stove but the draft is higher than that in the chimney. in another post i mentioned i used to have a draft gage on the stove and one on the chimney after the baro so i knew what the draft is on both. sometime the difference is zero or varies three to five hundreds. the amount that the baro is open will vary and is dependant on a couple of variables, your burn rate, atmospheric conditions and windy days.
i hear people say my baro just sits there and swings open and close constanly and i tell them thats how you know its working. without one on a windy day your fire will burn up quick especially on a handfired unit or it will start breathing because of a sudden updrafts followed by and sudden downdrafts.
when the baro is open under normal conditions and you lower the feed rate or on a manual stove are at the down side of a reload the baro will slowly close and then the stove and chimney are like in harmony working as one. if someone has set up your baro (pro) or you do it yourself and you set it at ?? you will know your draft is increasing when it starts to open and what the draft is at that point because you know the setpoint of opening providing the wind isnt ripping.
i hope this helps