What is the correct pronunciation of Rama in the mahamantra?

From: Seema Saraogi

Hare Krsna Pr. PAMHO. I recently visited Kolkata and saw that devotees pronounce in the mahamantra “RAMO” while everywhere we write “RAMA”. I being from hindi speaking background always pronounce “RAM”. Can you please elucidate on the pronunciation of the HK Mahamantra.

Relevant reference:

murkho vadati vishnaya      dhiro vadati vishnave

ubhayos tu samam punyam      bhava-grahi janardanah

“At the time of offering obeisances to Lord Vishnu, a foolish person chants vishnaya namah (this is improper due to faulty grammar) and a learned person chants vishnave namah (this is the correct form). But both achieve equal piety by their offering of obeisances, because Lord Shri Janardana sees the sentiment of the living being, in other words, He sees the degree of devotion, or in other words, He awards the result accordingly (He does not see one’s foolishness or intelligence).

CB Adi-khanda 11.108