Both approaches are valid, do know that this record will not show as the originating address. When you send an email to one of your configured addresses, the sending MTA will look up the MX record configured for your domain. It will get the IP from that domain and it will open an SMTP session with your SMTP server (or one of your SMTP servers if you have configured more than one).
Even without an MX record it will work, because then the MTA just looks up the A record for your domain. (providing your A record points to your SMTP server of course)